JP2017017248A - Light-emitting device and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device being capable of achieving high output while reducing a minimum amount of a current capable of forming an inverted population state.SOLUTION: A light-emitting device 100 according to the present invention includes: an active layer capable of generating light by injecting a current therethrough; a first cladding layer and a second cladding layer interposing the active layer therebetween; and electrodes injecting the current through the active layer. The active layer constitutes an optical waveguide 160 wave-guiding the light. The optical waveguide 160 has a resonator 180 in which the light wave-guided through the optical waveguide 160 does not oscillate.SELECTED DRAWING: Figure 1

Description

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

  A light emitting device such as a semiconductor laser or a super luminescent diode (hereinafter also referred to as “SLD”) is used as a light source of a projector, for example. SLDs are incoherent like ordinary light-emitting diodes, and exhibit a broad spectrum shape, but with an optical output characteristic, it is possible to obtain an output of up to several hundreds mW with a single element like a semiconductor laser. A semiconductor light emitting device.

  For example, Patent Document 1 describes an SLD having a portion extending in an inclined manner with respect to a normal line of an end surface.

JP 2012-43950 A

  However, in the SLD described in Patent Document 1, if the waveguide is lengthened to increase the output, the minimum amount of current that can form the inversion distribution state increases.

  One of the objects according to some embodiments of the present invention is to provide a light-emitting device capable of achieving high output while reducing the minimum amount of current that can form an inversion distribution state. Another object of some embodiments of the present invention is to provide a projector including the light-emitting device.

The light emitting device according to the present invention is
An active layer capable of generating light when current is injected;
A first cladding layer and a second cladding layer sandwiching the active layer;
An electrode for injecting current into the active layer;
Including
The active layer constitutes an optical waveguide for guiding light,
The optical waveguide has a resonator that does not oscillate light guided through the optical waveguide.

  In such a light emitting device, even if the length of the optical waveguide is not increased, the path through which the light guided through the optical waveguide is emitted to the outside can be increased, and high output can be achieved. Therefore, in such a light-emitting device, it is possible to increase the output while reducing the minimum amount of current that can form the inverted distribution state.

In the light emitting device according to the present invention,
The amount of light amplification in the resonator may be smaller than the amount of light loss in the resonator.

  Such a light-emitting device can have a resonator that does not oscillate light guided through the optical waveguide.

In the light emitting device according to the present invention,
The resonator includes a first reflecting portion and a second reflecting portion that are separated from each other and reflect light guided through the optical waveguide,
The first reflection unit and the second reflection unit are configured by a diffraction grating,
The diffraction grating may be formed by a concavo-convex structure periodically provided in the second cladding layer.

  In such a light emitting device, the light guided through the optical waveguide repeats multiple reflections between the first reflecting portion and the second reflecting portion of the resonator to form a standing wave, and is amplified by stimulated emission during that time. Can be done.

In the light emitting device according to the present invention,
R ₁ R ₂ exp (g-α) L <1
May be satisfied.
However, R ₁ is the reflectivity of the first reflector with respect to the cavity inside the guiding light between said second reflecting portion and the first reflection portion of the optical waveguide,
R ₂ is the reflectivity of the second reflecting portion with respect to the light guided inside the resonator,
g is the gain of light guided inside the resonator,
α is an internal loss of light guided through the resonator,
L is the resonator length of the resonator.

  Such a light-emitting device can have a resonator that does not oscillate light guided through the optical waveguide.

In the light emitting device according to the present invention,
The resonator includes a diffraction grating formed by a concavo-convex structure periodically provided in the second cladding layer,
The concavo-convex structure may be provided from one end of the resonator to the other end of the resonator as viewed from the stacking direction of the active layer and the first cladding layer.

  In such a light-emitting device, the light guided through the optical waveguide can be amplified by stimulated emission during which multiple reflections are repeated in the resonator to form a standing wave.

In the light emitting device according to the present invention,
κL <0.1
May be satisfied.
Where κ is the coupling coefficient between light traveling in one direction and light traveling in the opposite direction in the resonator,
L is the resonator length of the resonator.

  Such a light-emitting device can have a resonator that does not oscillate light guided through the optical waveguide.

In the light emitting device according to the present invention,
The resonator may have two different resonance wavelengths.

  In such a light emitting device, speckle noise can be reduced.

In the light emitting device according to the present invention,
The Q value of the resonator may be less than 1000.

  Such a light-emitting device can have a resonator that does not oscillate light guided through the optical waveguide.

In the light emitting device according to the present invention,
The optical waveguide may include a plurality of the resonators.

  In such a light emitting device, higher output can be achieved.

In the light emitting device according to the present invention,
The resonance wavelengths of the plurality of resonators may be different from each other.

  In such a light emitting device, it is possible to suppress the oscillation of light guided through the optical waveguide.

In the light emitting device according to the present invention,
The plurality of resonators may be provided symmetrically with respect to the center of the optical waveguide when viewed from the stacking direction of the active layer and the first cladding layer.

  In such a light emitting device, the difference between the intensity of the light emitted from the first light emitting surface and the intensity of the light emitted from the second light emitting surface can be reduced.

In the light emitting device according to the present invention,
The resonator may be provided including the center of the optical waveguide.

  In such a light emitting device, higher output can be achieved.

In the light emitting device according to the present invention,
The optical waveguide has a first light emitting surface and a second light emitting surface for emitting light,
The optical waveguide may extend in a direction inclined with respect to a normal line of the first light exit surface and the second light exit surface.

  Such a light emitting device can reduce speckle noise.

The projector according to the present invention is
A light emitting device 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.

  In such a projector, high brightness can be achieved.

The top view which shows typically the light-emitting device which concerns on 1st Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on 1st Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on 1st Embodiment. The schematic diagram which shows the output intensity with respect to the wavelength of light. The schematic diagram which shows the output intensity with respect to the wavelength of light. The figure for demonstrating the relationship between the position of the extension direction of an optical waveguide, and light intensity. The figure for demonstrating the relationship between the position of the extension direction of an optical waveguide, and the amount of carriers. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on 1st Embodiment. The top view which shows typically the light-emitting device which concerns on the 1st modification of 1st Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on the 2nd modification of 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on the 2nd modification of 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on the 2nd modification of 1st Embodiment. The top view which shows typically the light-emitting device which concerns on the 3rd modification of 1st Embodiment. The top view which shows typically the light-emitting device which concerns on 2nd Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on 2nd Embodiment. The schematic diagram which shows the output intensity with respect to the wavelength of light. The figure which shows typically the projector which concerns on 3rd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are essential constituent requirements of the present invention.

1. 1. First embodiment 1.1. First, the light emitting device according to the first embodiment will be described with reference to the drawings. FIG. 1 is a plan view schematically showing the light emitting device 100 according to the first embodiment. 2 is a cross-sectional view taken along the line II-II in FIG. 1 schematically showing the light emitting device 100 according to the first embodiment. 3 is a cross-sectional view taken along the line III-III of FIG. 1 schematically showing the light emitting device 100 according to the first embodiment.

  As shown in FIGS. 1 to 3, the light emitting device 100 includes a substrate 102, a first cladding layer 104, an active layer 106, a second cladding layer 108, a contact layer 110, an insulating layer 112, and a first layer. An electrode 120 and a second electrode 122 are included. For convenience, the second electrode 122 is omitted in FIG.

  The substrate 102 is, for example, a first conductivity type (for example, n-type) GaAs substrate.

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

  The active layer 106 is provided on the first cladding layer 104. 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.

As shown in FIG. 1, the active layer 106 has, for example, a rectangular shape when viewed from the stacking direction of the active layer 106 and the first cladding layer 104 (hereinafter also referred to as “in plan view”). The active layer 106 has a first side surface 105 and a second side surface 107. The side surfaces 105 and 107 are surfaces facing in opposite directions (parallel surfaces in the illustrated example), and the cladding layer 10
4, 108 is a surface not in contact with the surface. The side surfaces 105 and 107 may be cleavage surfaces formed by cleavage.

  The active layer 106 is a layer that can generate light by being injected with current. The active layer 106 constitutes an optical waveguide 160 that guides light. Light guided through the optical waveguide 160 can receive a gain in the optical waveguide 160.

  The optical waveguide 160 extends from the first side surface 105 to the second side surface 107. The optical waveguide 160 has a first light emission surface 170 and a second light emission surface 172 that emit light. The first light exit surface 170 is a connection portion with the first side surface 105 of the optical waveguide 160. The second light exit surface 172 is a connection portion with the second side surface 107 of the optical waveguide 160.

  The optical waveguide 160 extends in a direction inclined with respect to the normal line Q of the first light output surface 170 and the normal line R of the second light output surface 172. In the illustrated example, an imaginary straight line (center line A) passing through the center of the first light exit surface 170 and the center of the second light exit surface 172 extends in a direction inclined with respect to the normal lines Q and R. Yes. The optical waveguide 160 has a predetermined width in a plan view, and has a strip-like and linear longitudinal shape along the extending direction of the optical waveguide 160 (in the extending direction of the center line A).

  The optical waveguide 160 includes a resonator 180 that does not oscillate (laser oscillation) light guided through the optical waveguide 160. Specifically, the part constituted by the active layer 106 of the optical waveguide 160 has a resonator 180. The resonator 180 is provided including the center C of the optical waveguide 160. That is, the distance between the first light exit surface 170 and the center C is equal to the distance between the second light exit surface 172 and the center C, and the resonator 180 overlaps the center C in plan view. Is provided.

The resonator 180 includes a first reflecting portion 182 and a second reflecting portion 184 that reflect light guided through the optical waveguide 160. The reflection parts 182 and 184 are separated from each other. In the example shown in the figure, the resonator 180 is configured by reflecting portions 182 and 184 and a portion (intermediate portion) 186 inside the resonator between the first reflecting portion 182 and the second reflecting portion 184 of the optical waveguide 160. Has been. The resonator 180 is a DBR (Distributed Bragg Reflector) type resonator. Specifically, the reflection parts 182 and 184 constitute a DBR. The reflecting portions 182 and 184 are configured by a diffraction grating in which a high refractive index region 18 and a low refractive index region 28 having a lower refractive index than the high refractive index region 18 are alternately arranged in the direction of the center line A of the optical waveguide 160. Has been. In the illustrated example, the refractive index regions 18 and 28 have a rectangular shape in plan view, and the long sides of the refractive index regions 18 and 28 are orthogonal to the center line A. Assuming that the effective refractive index in the high refractive index region 18 is n _{1, the} effective refractive index in the low refractive index region 28 is n _2, and the wavelength of the light guided through the intermediate portion 186 of the optical waveguide 160 in vacuum is λ, For example, the length of the high refractive index region 18 in the direction of the center line A is λ / (4n ₁ ), and the length of the low refractive index region 28 in the direction of the center line A is λ / (4n ₂ ).

  The resonator 180 may be a Fabry-Perot type resonator. Specifically, the reflecting portions 182 and 184 do not have to be configured by a diffraction grating. For example, it may be configured by only one of the high refractive index region 18 and the low refractive index region 28, or may be configured by only a pair of the high refractive index region 18 and the low refractive index region 28.

The amount of light amplification in the resonator 180 (light guided through the optical waveguide 160) is smaller than the amount of light loss in the resonator 180. Here, the “amplification amount of light in the resonator 180” is a change amount of light intensity amplified by receiving a gain while the light generated in the resonator 180 is emitted to the outside of the resonator 180. The “loss of light in the resonator 180” means an internal loss or a mirror loss (loss in the reflectors 182 and 184) while the light generated in the resonator 180 is emitted to the outside of the resonator 180. ) Is the amount of change in light intensity reduced. Specifically, the light generated in the resonator 180 is amplified by being guided through the optical waveguide 160, but the reflectance of the reflecting portions 182 and 184 is low, and the distance L between the reflecting portions 182 and 184 is small. Therefore, the overall gain of the resonator 180 is less than 1. More specifically, the resonator 180 satisfies the following formula (1). Accordingly, the light emitting device 100 can include the resonator 180 that does not oscillate the light guided through the optical waveguide 160.

R ₁ R ₂ exp (g-α) L <1 (1)

In Equation (1), R ₁ is the reflectance of the first reflecting portion 182 with respect to the light guided through the intermediate portion 186 of the optical waveguide 160, and R ₂ is guided through the intermediate portion 186 of the optical waveguide 160. Is the reflectance of the second reflecting part 184 with respect to the light to be transmitted, g is the gain of the light guided through the intermediate part 186 of the optical waveguide 160, and α is the light of the light guided through the intermediate part 186 of the optical waveguide 160. It is an internal loss, and L is the resonator length of the resonator 180 (specifically, the distance between the first reflecting portion 182 and the second reflecting portion 184).

Note that the values of R ₁ , R ₂ , and L are not particularly limited as long as the expression (1) is satisfied. For example, when the gain of the multiple quantum well is about 2000 cm ⁻¹ , R ₁ and R ₂ are set to 0. It is 0000001 or more and 0.02 or less, and L is 2 μm or more and 160 μm or less. The reflectances R ₁ and R ₂ can be reduced by reducing the difference in refractive index between the refractive index regions 18 and 28 or by reducing the period of the concavo-convex structures 12 and 14 described later.

  The Q value of the resonator 180 is, for example, less than 1000. The Q value is approximately equal to the resonance frequency divided by the half width, and if the Q value is 1000 or more, oscillation may occur in the resonator. The Q value satisfies the following formula (2).

Q = 4πL / {λ (1-R ₁ −R ₂ )} (2)

However, in Formula (2), L is the resonator length of the resonator 180, λ is the wavelength of light guided through the intermediate portion 186 of the optical waveguide 160, and R ₁ is between the optical waveguides 160. The reflectance of the first reflecting portion 182 with respect to the light guided through the portion 186, and R ₂ is the reflectance of the second reflecting portion 184 with respect to the light guided through the intermediate portion 186 of the optical waveguide 160. Expression (2) is an expression for approximately obtaining the Q value. If the Q value obtained by Expression (2) is less than 1000, the resonator 180 guides the optical waveguide 160. Light does not oscillate. For example, when the gain of the previous multiple quantum well is 2000 cm ⁻¹ , if R ₁ = R ₂ = 0.01 and L = 40 μm, then Q = 2500, and even if α = 0 cm ⁻¹ Satisfies and does not oscillate.

Here, FIG. 4 is a schematic diagram showing the output intensity with respect to the wavelength of the light emitted from the light emitting device 100. In the light emitting device 100, since the resonator 180 is a DBR type or Fabry-Perot type resonator, the number of wavelengths that form a standing wave in the resonator 180 is often plural (a plurality of resonance wavelengths). As shown in FIG. 4, the resonance component of light becomes multimode. Therefore, the spec noise can be reduced in the light emitting device 100. The “resonance component” is light that forms a standing wave in the resonator 180 among the light guided through the optical waveguide 160, and the “SLD component” is guided through the optical waveguide 160. Of the light, the light is transmitted without being reflected by the first reflecting portion 182 and the second reflecting portion 184, and does not form a standing wave at the resonator 180. Further, here, since a resonator that does not oscillate is configured, it means that there are a plurality of resonance modes (wavelengths), not oscillation modes (wavelengths). Therefore, by reducing the reflectivity _R 1, _{R 2} of the first reflecting portion 182 and the second reflecting portion 184, also as a reflection band of the first reflecting portion 182 and the second reflecting portion 184 is narrowed, the resonant wavelength Are plural.

FIG. 5 shows the peak P shown in FIG. 4 separated by a known method. For example, the Q value can be estimated from the ratio (ω _P / Δω _P ) between the resonance angular frequency ω _P of the peak P and the half-value width _Δ ω _P of the peak P. Note that ω _P / Δω _P is approximately obtained from the following formula (3) based on the ratio (λ _P / Δλ _P ) between the resonance wavelength λ _P of the peak P and the half-value width Δλ _P of the peak P. Can do.

ω _P / Δω _P = ω _P / (ω _L −ω _H ) = (λ _L λ _H ) / (λ _L −λ _H ) λ _P
= (Λ _L λ _H ) / Δλ _P λ _P ≈λ _P ² / Δλ _P λ _P = λ _P / Δλ _P (3)

However, in Formula (3), ω _P = 2πc / λ _P , ω _H = 2πc / λ _H , and ω _L = 2πc / λ _L.

  As shown in FIGS. 2 and 3, the second cladding layer 108 is provided on the active layer 106. The second cladding layer 108 is, for example, a second conductivity type (eg, p-type) semiconductor layer. The cladding layers 104 and 108 are layers having a larger band gap and a lower refractive index than the active layer 106. The clad layers 104 and 108 have a function of suppressing leakage of injected carriers (electrons and holes) and light with the active layer 106 interposed therebetween.

The second cladding layer 108 has a first layer 118, a protrusion 128, and a second layer 138. The first layer 118 is provided on the active layer 106. The thickness of the first layer 118 is, for example, about several tens nm to several hundreds nm. The material of the first layer 118 is, for example, In _0.52 Al _0.48 P.

  The protrusion 128 of the second cladding layer 108 is provided on the first layer 118. The protrusion 128 protrudes upward from the first layer 118. The protrusions 128 are provided periodically. As a result, a concavo-convex structure provided periodically is formed in the second cladding layer 108. In the illustrated example, the protrusions 128 are periodically provided to form the first uneven structure 12, and the protrusions 128 are periodically provided apart from the first uneven structure 12 to form the second uneven structure 14. Has been.

The protrusion 128 of the second cladding layer 108 is made of a material having a higher refractive index than the first layer 118 and the second layer 138. The material of the protrusion 128 is, for example, InGaAlP having an Al composition smaller than that of the first layer 118 and the second layer 138 and larger than or equal to that of the barrier layer constituting the active layer 106. Specifically, the material of the protrusion 128 is In _0.52 (Ga _0.4 Al _0.6 ) _0.48 P.

  The first concavo-convex structure 12 of the second cladding layer 108 overlaps the first reflecting portion 182 in plan view. The diffraction grating constituting the first reflecting portion 182 is formed by the first concavo-convex structure 12. The second concavo-convex structure 14 overlaps the second reflecting portion 184 in plan view. The diffraction grating constituting the second reflecting portion 184 is formed by the second concavo-convex structure 14. For example, in plan view, the high refractive index region 18 of the diffraction grating is a portion that overlaps with the protrusion 128, and the low refractive index region 28 is a portion that does not overlap with the protrusion 128.

  The second layer 138 of the second cladding layer 108 is provided on the first layer 118 and the protrusions 128. The material of the second layer 138 is the same as the material of the first layer 118, for example.

In the illustrated example, the concavo-convex structures 12 and 14 are formed by the protrusions 128 protruding upward from the first layer 118 of the second cladding layer 108.
14 may be formed by an opening provided in the second cladding layer 108. In this case, the second cladding layer 108 may be composed of one layer.

  In the light emitting device 100, 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. In the light emitting device 100, when a forward bias voltage of a pin diode is applied between the electrodes 120 and 122 (current is injected), an optical waveguide 160 is generated in the active layer 106, and electrons and holes are regenerated in the optical waveguide 160. Bonding occurs. This recombination causes light emission. With this generated light as a starting point, stimulated emission occurs in a chain, and the intensity of the light is amplified in the optical waveguide 160. The optical waveguide 160 includes an active layer 106 that guides light and clad layers 104 and 108 that suppress light leakage.

  For example, as shown in FIG. 1, the light 10 generated in the vicinity of the first light emitting surface 170 of the optical waveguide 160 and directed toward the second light emitting surface 172 is emitted from the first reflecting portion 182 and the first light emitting surface of the optical waveguide 160. In the portion between the surface 170, after being amplified, the resonator 180 is reached. The light 10 that has reached the resonator 180 repeats multiple reflections between the reflecting portions 182 and 184 of the resonator 180 to form a standing wave, and is amplified by stimulated emission during that time. Here, the light emitting device 100 satisfies the formula (1), and the Q value of the resonator 180 is less than 1000. Therefore, the light 10 that repeats multiple reflections between the reflecting portions 182 and 184 transmits, for example, the second reflecting portion 184 without oscillating. Then, the light 10 transmitted through the second reflecting portion 184 is further amplified and emitted from the second light emitting surface 172 in the portion of the optical waveguide 160 between the second reflecting portion 184 and the second light emitting surface 172. Is done.

  The light that repeats multiple reflections between the reflection units 182 and 184 may pass through the first reflection unit 182. In this case, the light transmitted through the first reflecting portion 182 is amplified at a portion of the optical waveguide 160 between the first reflecting portion 182 and the first light emitting surface 170, and is transmitted from the first light emitting surface 170 to the outside. It is injected.

  Similarly, light that occurs near the second light exit surface 172 of the optical waveguide 160 and travels toward the first light exit surface 170 repeats multiple reflections between the reflecting portions 182 and 184 of the resonator 180 to form a standing wave. In the meantime, it is amplified by stimulated emission. And the light which repeats multiple reflection between the reflection parts 182 and 184 does not oscillate, for example, permeate | transmits the 1st reflection part 182, and is inject | emitted from the 1st light-projection surface 170 outside.

  As shown in FIGS. 2 and 3, the contact layer 110 is provided on the second cladding layer 108. The contact layer 110 is in ohmic contact with the second electrode 122. For example, the planar shape of the upper surface (contact surface with the second electrode 122) of the contact layer 110 is the same as the planar shape of the optical waveguide 160. The contact layer 110 is, for example, a p-type GaAs layer.

  The contact layer 110 and a part of the second cladding layer 108 constitute a columnar portion 111 as shown in FIG. The planar shape of the columnar part 111 is the same as the planar shape of the optical waveguide 160, for example. For example, the current path between the electrodes 120 and 122 is determined by the planar shape of the columnar portion 111, and as a result, the planar shape of the optical waveguide 160 is determined. Although not shown, the side surface of the columnar part 111 may be inclined.

The insulating layer 112 is provided on the second cladding layer 108 and on the side of the columnar portion 111 (around the columnar portion 111 in plan view). The insulating layer 112 is in contact with the side surface of the columnar part 111. The upper surface of the insulating layer 112 may be continuous with the upper surface of the contact layer 110 as shown in FIG. The insulating layer 112 is, for example, a SiN layer, a SiO ₂ layer, a SiON layer, or Al ₂
O ₃ layer, polyimide layer. When the above material is used for the insulating layer 112, the current between the electrodes 120 and 122 flows through the columnar portion 111 sandwiched between the insulating layers 112, avoiding the insulating layer 112.

  The insulating layer 112 has a refractive index smaller than that of the second cladding layer 108. The effective refractive index of the vertical section of the portion where the insulating layer 112 is formed is smaller than the effective refractive index of the vertical section of the portion where the insulating layer 112 is not formed, that is, the portion where the columnar portion 111 is formed. Thereby, light can be efficiently confined in the optical waveguide 160 in the planar direction. Note that although not illustrated, the insulating layer 112 is not necessarily provided. In this case, the air surrounding the columnar portion 111 performs the same function as the insulating layer 112.

  The first electrode 120 is provided under the substrate 102. The first electrode 120 is provided on the lower surface of a layer (substrate 102 in the illustrated example) that is in ohmic contact with the first electrode 120. The first electrode 120 is one electrode for driving the light emitting device 100 (injecting current into the active layer 106). As the first electrode 120, for example, an electrode 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 is used.

  The second electrode 122 is provided on the contact layer 110. In the example shown in FIG. 3, the second electrode 122 is further provided on the insulating layer 112. The second electrode 122 is the other electrode for driving the light emitting device 100 (injecting current into the active layer 106). As the second electrode 122, for example, an electrode in which a Cr layer, an AuZn layer, and an Au layer are stacked in this order from the contact layer 110 side is used.

  Although the AlGaInP-based light emitting device 100 has been described above, the light emitting device according to the present invention can use any material system that can form an optical waveguide. As the semiconductor material, for example, semiconductor materials such as AlGaN, GaN, InGaN, GaAs, AlGaAs, InGaAs, InGaAsP, InP, GaP, AlGaP, and ZnCdSe can be used.

  In the above, the light-emitting device 100 is provided with a difference in refractive index between a region where the insulating layer 112 is formed and a region where the insulating layer 112 is not formed, that is, a region where the columnar portion 111 is formed. This is described as a so-called refractive index waveguide type that confines light. Although not shown, the light-emitting device according to the present invention does not provide a difference in refractive index by forming the columnar portion 111, and the so-called gain guide in which the optical waveguide 160 generated by injecting current becomes the waveguide region as it is. It may be corrugated.

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

  For example, the light emitting device 100 has the following characteristics.

  In the light emitting device 100, the optical waveguide 160 includes a resonator 180 that does not oscillate light guided through the optical waveguide 160. Therefore, in the light emitting device 100, the light guided through the optical waveguide 160 is repeatedly reflected multiple times between the reflecting portions 182 and 184 of the resonator 180 to form a standing wave, and during that time, it can be amplified by stimulated emission. it can. Therefore, in the light emitting device 100, even if the length of the optical waveguide 160 in the direction of the center line A is not increased, the path until the light guided through the optical waveguide 160 is emitted to the outside can be increased, and the high output Can be achieved. Therefore, in the light emitting device 100, it is possible to increase the output while reducing the minimum amount of current that can form the inverted distribution state.

  Further, in the light emitting device 100, since the minimum amount of current that can form the inverted distribution state can be reduced, the amount of heat generated in the light emitting device 100 can be reduced, and the temperature characteristics can be improved. . Furthermore, since the amount of heat discharged in the light emitting device 100 can be reduced, the size of the projector housing can be reduced when the light emitting device 100 is used in a projector.

  Furthermore, in the light emitting device 100, since the length of the optical waveguide 160 in the direction of the center line A does not need to be increased, the size can be reduced accordingly, and the number of light emitting devices manufactured from one wafer. Can be increased. Therefore, the cost can be reduced and the amount of resources used can be reduced, which is good for the environment.

  Further, in the light emitting device 100, the light guided through the optical waveguide 160 does not oscillate in the resonator 180, so that the light emitting device 100 can function as an SLD (the light emitting device 100 is an SLD). Therefore, the light emitting device 100 can reduce speckle noise.

  In the light emitting device 100, the amount of light amplification in the resonator 180 is smaller than the amount of light loss in the resonator 180. Specifically, the light emitting device 100 satisfies the formula (1). Therefore, the light emitting device 100 can include a resonator 180 that does not oscillate light guided through the optical waveguide 160.

  In the light emitting device 100, the Q value of the resonator 180 is less than 1000. Therefore, the light emitting device 100 can constitute a resonator 180 that does not oscillate light guided through the optical waveguide 160.

  In the light emitting device 100, the resonator 180 is provided including the center C of the optical waveguide 160. Therefore, the light emitting device 100 can achieve higher output. The reason will be described below.

FIG. 6 is a diagram for explaining the relationship between the position in the extending direction of the optical waveguide and the light intensity. FIG. 7 is a diagram for explaining the relationship between the position in the extending direction of the optical waveguide and the amount of carriers. The position in the extending direction of the optical waveguide on the horizontal axis in FIGS. 6 and 7 is between the first light exit surface (one end of the optical waveguide) and the second light exit surface (the other end of the optical waveguide). The position in the extending direction of the optical waveguide is shown. 6, the intensity I ₁ of the light traveling from the first light exit surface to the second light emitting surface, and the intensity I ₂ of the light from the second light exit surface toward the first light exit surface, the intensity I ₁ and the intensity I ₂ and the total intensity I _TOTAL .

In general, in SLD, light is amplified exponentially toward a light exit surface (side with a low reflectance). Therefore, as shown in FIG. 6, the light intensity has a non-uniform distribution in the extending direction of the optical waveguide. The distribution of the intensity I _TOTAL is substantially the same as the distribution of the consumed carrier amount at the position in the extending direction of the optical waveguide. Accordingly, as shown in FIG. 7, when the injected current amount per unit length is constant in the extending direction of the optical waveguide, the carrier consumption is large in the vicinity of the light exit surface, and the light consumption (with respect to the photon) E) Career is relatively short. That is, when light is about to be amplified, there are not enough carriers to be converted to light (excess or deficiency of carriers occurs). As a result, gain saturation occurs in the vicinity of the light exit surface where the light intensity is high, and the light output is reduced accordingly.

  On the other hand, in the region including the center C of the optical waveguide, there are more carriers than in the vicinity of the light emitting surface, and the carriers are not sufficiently converted to light, and there are surplus carriers (excess carriers are generated).

  As described above, in the light emitting device 100, the resonator 180 is provided so as to include the center C of the optical waveguide 160, so that light can be multiple-reflected in a region including the center C. Thereby, in the light emitting device 100, the carrier consumption can be increased in the region including the center C, and the surplus carrier amount can be reduced. Therefore, the light emitting device 100 can achieve higher output.

  In the light emitting device 100, the optical waveguide 160 extends in a direction inclined with respect to the normal lines Q and R of the light emitting surfaces 170 and 172. Therefore, in the light emitting device 100, it is possible to suppress the multiple reflection of the light guided through the optical waveguide 160 between the light emitting surfaces 170 and 172. Thereby, in the light-emitting device 100, since a direct resonator cannot be comprised, the laser oscillation of the light guided through the optical waveguide 160 can be suppressed. As a result, the light emitting device 100 can reduce speckle noise.

1.2. Method for Manufacturing Light-Emitting Device Next, a method for manufacturing the light-emitting device 100 according to the first embodiment will be described with reference to the drawings. 8-10 is sectional drawing which shows typically the manufacturing process of the light-emitting device 100 which concerns on 1st Embodiment.

  As shown in FIG. 8, the first cladding layer 104, the active layer 106, the first layer 118, and the high refractive index layer 128a are epitaxially grown in this order on the substrate 102. Examples of the epitaxial growth method include a MOCVD (Metal Organic Chemical Deposition) method and an MBE (Molecular Beam Epitaxy) method.

  As shown in FIG. 9, the high refractive index layer 128a is patterned to form a plurality of protrusions 128. The patterning is performed by, for example, photolithography and etching. For example, after forming the outer shape of the inclined surface by RIE (Reactive Ion Etching) and then performing anisotropic etching (wet etching), the protrusion 128 having a flat inclined surface can be formed.

  As shown in FIG. 10, the second layer 138 and the contact layer 110 are epitaxially grown in this order on the first layer 118 a and the protrusions 128. Examples of the epitaxial growth method include MOCVD method and MBE method. By this step, the second cladding layer 108 can be formed.

  As shown in FIG. 3, the contact layer 110 and the second cladding layer 108 are patterned to form a columnar portion 111. The patterning is performed by, for example, photolithography and etching.

  Next, the insulating layer 112 is formed so as to cover the side surface of the columnar part 111. Specifically, first, an insulating member (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, for example, by etching. Through the above steps, the insulating layer 112 can be formed.

  As shown in FIGS. 2 and 3, the second electrode 122 is formed on the contact layer 110. Next, the first electrode 120 is formed on the lower surface of the substrate 102. The electrodes 120 and 122 are formed by, for example, a vacuum deposition method or a sputtering method. Note that the order of forming the electrodes 120 and 122 is not particularly limited.

  Through the above steps, the light emitting device 100 can be manufactured.

1.3. Modified example of light emitting device 1.3.1. First Modification Next, a light-emitting device according to a first modification of the first embodiment will be described with reference to the drawings. FIG. 11 is a plan view schematically showing a light emitting device 200 according to a first modification of the first embodiment. For convenience, the second electrode 122 is omitted in FIG.

  Hereinafter, in the light emitting device 200 according to the first modification of the first embodiment, members having the same functions as those of the constituent members of the light emitting device 100 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is given. Is omitted. The same applies to the light emitting devices according to the second and third modifications of the first embodiment described below.

  In the light emitting device 100 described above, the optical waveguide 160 has one resonator 180 as shown in FIG. On the other hand, in the light emitting device 200, the optical waveguide 160 has a plurality of resonators 180 as shown in FIG.

  In the light emitting device 200, the number of the resonators 180 is not particularly limited, but in the example illustrated, the light emitting device 200 includes two resonators 180a and 180b. The first resonator 180a is provided closer to the first light exit surface 170 than the center C of the optical waveguide 160, and the second resonator 180b is provided closer to the second light exit surface 172 than the center C of the optical waveguide 160. It has been. The resonators 180a and 180b are provided symmetrically with respect to the center C of the optical waveguide 160 in a plan view, for example. For example, the resonators 180a and 180b may be provided symmetrically with respect to a virtual straight line B passing through the center C of the optical waveguide 160 and orthogonal to the extending direction of the optical waveguide 160 (in the center line A) in plan view.

  The resonance wavelengths of the resonators 180a and 180b are different from each other, for example. That is, the wavelength of light that forms a standing wave in the first resonator 180a is different from the wavelength of light that forms a standing wave in the first resonator 180a. For example, the length in the center line A direction of the protrusion 128 provided above the reflecting portions 182 and 184 of the first resonator 180a and the protrusion provided above the reflecting portions 182 and 184 of the second resonator 180b. By making the length of 128 in the direction of the center line A different, the resonance wavelengths of the resonators 180a and 180b can be made different from each other. For example, after the formation of the first layer 118 and the high refractive index layer 128a of the second cladding layer 108 (see, for example, FIG. 8), the center line A is located above the regions to be the reflective portions 182 and 184 of the first resonator 180a. The first high refractive index region having a predetermined length in the direction is located above the regions to be the reflecting portions 182 and 184 of the second resonator 180b, and the length in the center line A direction is the first high refractive index region. Second high refractive index regions different from those are formed by patterning. Thereby, the protrusion part 128 from which the length of the centerline A direction differs can be formed. Note that the resonance wavelengths of the resonators 180a and 180b may be the same.

  The light emitting device 200 has the following features, for example.

  In the light emitting device 200, the optical waveguide 160 has a plurality of resonators 180. Therefore, in the light emitting device 200, for example, the light 10 generated in the vicinity of the first light emitting surface 170 is emitted from the second light emitting surface 172, as compared with the case where the optical waveguide 160 has one resonator 180. In this case, the path until the light 10 reaches the second light exit surface 172 can be lengthened. Therefore, the amount of amplification of the light 10 can be increased, and higher output can be achieved.

In the light emitting device 200, the resonance wavelengths of the plurality of resonators 180 are different from each other. Therefore, in the light emitting device 200, it is possible to suppress the light guided through the optical waveguide 160 from oscillating. For example, when the resonance wavelengths of a plurality of resonators are the same as each other, light emitted from one resonator may oscillate with a high Q value because of multiple reflection in another resonator.

  In the light emitting device 200, the plurality of resonators 180 are provided symmetrically with respect to the center C of the optical waveguide 160 in plan view. For this reason, in the light emitting device 200, for example, the intensity of the light emitted from the first light emitting surface 170 and the light emitted from the second light emitting surface 172 are compared with the case where the light emitting device 200 is provided asymmetrically with respect to the center of the optical waveguide. The difference between the strength and the strength can be reduced.

1.3.2. Second Modified Example Next, a light emitting device according to a second modified example of the first embodiment will be described with reference to the drawings. FIG. 12 is a cross-sectional view schematically showing a light emitting device 300 according to a second modification of the first embodiment.

  In the light emitting device 100 described above, as shown in FIG. 2, the first layer 118 and the second layer 138 of the second cladding layer 108 are made of the same material, and the protrusion 128 and the first layer of the second cladding layer 108 are the same. 118 was a different material.

On the other hand, in the light emitting device 300, as shown in FIG. 12, the first layer 118 and the second layer 138 are made of different materials, and the protruding portion 128 and the first layer 118 are made of the same material and integrated. Provided. The second layer 138 is made of a material having a higher refractive index than the first layer 118 and the protrusions 128. Specifically, the material of the first layer 118 is, for example, In _0.52 Al _0.48 P, and the material of the second layer 138 is, for example, In _0.52 (Ga _0.1 Al _0.9 ) _0.48 P.

  Next, a method for manufacturing the light emitting device 300 according to the second modification of the first embodiment will be described with reference to the drawings. 13 and 14 are cross-sectional views schematically showing the manufacturing process of the light emitting device 300 according to the second modification of the first embodiment.

  Hereinafter, in the method for manufacturing the light emitting device 300 according to the second modification of the first embodiment, differences from the example of the method for manufacturing the light emitting device 100 according to the first embodiment will be described, and description of similar points will be omitted. To do.

  As shown in FIG. 13, on the substrate 102, the first cladding layer 104, the active layer 106, and the first layer 118 are epitaxially grown in this order.

  As shown in FIG. 14, the first layer 118 is patterned to form a plurality of protrusions 128. Next, the second layer 138 and the contact layer 110 are epitaxially grown in this order on the first layer 118 and the protrusions 128.

1.3.3. Third Modification Next, a light-emitting device according to a third modification of the first embodiment will be described with reference to the drawings. FIG. 15 is a plan view schematically showing a light emitting device 400 according to a third modification of the first embodiment. For convenience, the second electrode 122 is omitted in FIG.

In the light emitting device 100 described above, as shown in FIG. 1, one optical waveguide 160 is provided. On the other hand, in the light emitting device 400, as shown in FIG. 15, a plurality of optical waveguides 160 are provided. In the illustrated example, three optical waveguides 160 are provided, but the number is not particularly limited.

  The light emitting device 400 can achieve higher output than the light emitting device 100, for example.

2. Second Embodiment 2.1. Next, a light emitting device according to a second embodiment will be described with reference to the drawings. FIG. 16 is a plan view schematically showing a light emitting device 500 according to the second embodiment. FIG. 17 is a cross-sectional view taken along the line XVII-XVII in FIG. 16 schematically illustrating the light emitting device 500 according to the second embodiment. For the sake of convenience, the second electrode 122 is omitted in FIG.

  Hereinafter, in the light emitting device 500 according to the second embodiment, members having the same functions as the constituent members of the light emitting device 100 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the light emitting device 100 described above, as shown in FIGS. 1 and 2, the resonator 180 is a Fabry-Perot resonator (specifically, a DBR resonator). On the other hand, in the light emitting device 500, as shown in FIGS. 16 and 17, the resonator 180 is a DFB (Distributed Feedback) type resonator.

  In the light emitting device 500, the resonator 180 includes a diffraction grating in which the high refractive index regions 18 and the low refractive index regions 28 are alternately arranged in the center line A direction of the optical waveguide 160. In the illustrated example, the protrusions 128 are periodically provided to form the third uneven structure 16, and the third uneven structure 16 overlaps the resonator 180 in plan view. The diffraction grating constituting the resonator 180 is formed by the third concavo-convex structure 16. The third concavo-convex structure 16 is provided from one end 8 on the first light exit surface 170 side of the resonator 180 to the other end 9 on the second light exit surface 172 side of the resonator 180 in plan view.

  The resonator 180 satisfies the following formula (4). Accordingly, the light emitting device 100 can include the resonator 180 that does not oscillate the light guided through the optical waveguide 160.

  κL <0.1 (4)

  Here, κ is a coupling coefficient between light traveling in one direction (one direction parallel to the center line A) and light traveling in the other (opposite direction parallel to the center line A) in the resonator 180, L is the resonator length (specifically, the length of the resonator 180 in the direction of the center line A and the distance between the ends 8 and 9). Here, the coupling coefficient κ is a table representing the distributed feedback rate of light by the diffraction grating, and depends on the difference between the refractive index of the high refractive index region 18 and the refractive index of the low refractive index region 28 of the diffraction grating. In general, the DFB laser is designed so that κL is about 1, and the resonator 180 that does not oscillate can be formed by making κL less than 0.1 as shown in Equation (4). The coupling coefficient κ can be expressed as the following formula (5).

κ = {n _eff (Δω) _gap } / 2c (5)

Where n _eff is the effective refractive index of light traveling through the optical waveguide 160, (Δω) _gap is the reflection band (reflection angular frequency band) of the diffraction grating, and c is the speed of light in vacuum. is there.

For example, κL can be reduced by reducing the difference between the refractive index regions 18, 28, reducing the period of the third uneven structure 16, or reducing the resonator length L.

  Here, FIG. 18 is a schematic diagram showing the output intensity with respect to the wavelength of the light emitted from the light emitting device 500. In the light emitting device 500, since the resonator 180 is a DFB type resonator, the resonance component of light is a single mode or two modes. In the illustrated example, the resonance component of light is a two-mode, and the resonator 180 has two different resonance wavelengths. Therefore, in the light emitting device 500, speckle noise can be reduced as compared with, for example, a case where the resonance component of light is a single mode.

2.2. Method for Manufacturing Light Emitting Device Next, a method for manufacturing the light emitting device 500 according to the second embodiment will be described. The manufacturing method of the light emitting device 500 according to the second embodiment is basically the same as the manufacturing method of the light emitting device 100 according to the first embodiment. Therefore, the description is omitted.

3. Third Embodiment Next, a projector according to a third embodiment will be described with reference to the drawings. FIG. 19 is a diagram schematically illustrating a projector 900 according to the third embodiment.

  As shown in FIG. 19, the projector 900 includes a red light source 400R that emits red light, green light, and blue light, a green light source 400G, and a blue light source 400B. The red light source 400R, the green light source 400G, and the blue light source 400B are light emitting devices according to the present invention. Hereinafter, an example in which the light emitting device 400 is used as the light emitting device according to the present invention will be described. For the sake of convenience, in FIG. 19, the casing that constitutes the projector 900 is omitted, and the light sources 400R, 400G, and 400B are simplified.

  The projector 900 further includes lens arrays 902R, 902G, and 902B, transmissive liquid crystal light valves (light modulation devices) 904R, 904G, and 904B, and a projection lens (projection device) 908.

  Light emitted from the light sources 400R, 400G, and 400B is incident on the lens arrays 902R, 902G, and 902B. The lens arrays 902R, 902G, and 902B have incident surfaces 901 on which light emitted from the first light emitting surface 170 is incident on the light sources 400R, 400G, and 400B side. The incident surface 901 is, for example, a flat surface. A plurality of incident surfaces 901 are provided corresponding to the plurality of first light emitting surfaces 170 and are arranged at equal intervals. A normal line (not shown) of the incident surface 901 is inclined with respect to the first side surface 105. By the incident surface 901, the optical axis of the light emitted from the first light emitting surface 170 can be made orthogonal to the irradiation surface 905 of the liquid crystal light valves 904R, 904G, and 904B.

  The lens arrays 902R, 902G, and 902B have an emission surface 903 on the liquid crystal light valves 904R, 904G, and 904B side. The emission surface 903 is, for example, a convex surface. A plurality of exit surfaces 903 are provided corresponding to the plurality of entrance surfaces 901 and are arranged at equal intervals. The light whose optical axis is converted on the incident surface 901 can be superposed (partially superposed) by being condensed by the exit surface 903 or by reducing the diffusion angle. Thereby, the liquid crystal light valves 904R, 904G, and 904B can be irradiated with good uniformity.

  As described above, the lens arrays 902R, 902G, and 902B can condense the light by controlling the optical axis of the light emitted from the first light emitting surface 170.

The light condensed by the lens arrays 902R, 902G, and 902B is incident on the liquid crystal light valves 904R, 904G, and 904B. Each of the liquid crystal light valves 904R, 904G, and 904B modulates incident light according to image information. The projection lens 908 enlarges and projects the image formed by the liquid crystal light valves 904R, 904G, and 904B onto a screen (display surface) 910.

  In addition, the projector 900 can include a cross dichroic prism (color light combining unit) 906 that combines light emitted from the liquid crystal light valves 904R, 904G, and 904B and guides the light to the projection lens 908.

  The three color lights modulated by the liquid crystal light valves 904R, 904G, and 904B are incident on the cross dichroic prism 906. 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 910 by the projection lens 908 which is a projection optical system, and an enlarged image is displayed.

  In the example shown in FIG. 19, the light emitted from the second light emitting surface 172 provided on the second side surface 107 is not shown, but the light is incident on the reflection unit and the lens array (not shown). Then, the light may enter the liquid crystal light valves 904R, 904G, and 904B.

  The projector 900 includes a light emitting device that can increase the output while reducing the minimum amount of current that can form the inverted distribution state. Therefore, the projector 900 can achieve high brightness.

  The projector 900 is a method (backlight method) in which the light emitting device 400 is disposed immediately below the liquid crystal light valves 904R, 904G, and 904B, and condensing and uniform illumination are performed simultaneously using the 902R, 902G, and 902B. Therefore, the projector 900 can reduce the loss of the optical system and the number of parts.

  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 reflection type liquid crystal light valve and a digital micromirror device (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 source 400R, 400G, 400B has scanning means that is an image forming apparatus that displays an image of a desired size on the display surface by causing the light from the light source 400R, 400G, 400B to scan on the screen. The present invention can also be applied to a light source device of a simple scanning image display device (projector).

  The above-described embodiments and modifications are merely examples, and the present invention is not limited to these. For example, it is possible to appropriately combine each embodiment and each modification.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

8, 9 ... edge, 10 ... light, 12 ... first uneven structure, 14 ... second uneven structure, 16 ... third uneven structure, 18 ... high refractive index region, 28 ... low refractive index region, 100 ... light emitting device, DESCRIPTION OF SYMBOLS 102 ... Substrate, 104 ... 1st clad layer, 105 ... 1st side surface, 106 ... Active layer, 107 ... 2nd side surface, 108 ... 2nd clad layer, 110 ... Contact layer, 111 ... Columnar part, 112 ... Insulating layer, 118: First layer, 120: First electrode, 122: Second electrode, 128: Projection, 128a: High refractive index layer, 138: Second layer, 160: Optical waveguide, 170: First light exit surface, 172 DESCRIPTION OF SYMBOLS 2nd light-projection surface, 180 ... Resonator, 180a ... 1st resonator, 180b ... 2nd resonator, 182 ... 1st reflection part, 184 ... 2nd reflection part, 186 ... Between part, 200,300,400 ... light emitting device, 400R, 400G, 400B ... light source, 500 Emitting device, 900 ... projector, 901 ... incident plane, 902R, 902G, 902B ... lens array, 904R, 904G, 904B ... liquid crystal light valve, 905 ... irradiation surface, 906 ... cross dichroic prism 908 ... projection lens 910 ... screen

Claims (14)

An active layer capable of generating light when current is injected;
A first cladding layer and a second cladding layer sandwiching the active layer;
An electrode for injecting current into the active layer;
Including
The active layer constitutes an optical waveguide for guiding light,
The light-emitting device, wherein the optical waveguide includes a resonator that does not oscillate light guided through the optical waveguide.   The light emitting device according to claim 1, wherein an amount of light amplification in the resonator is smaller than an amount of light loss in the resonator. The resonator includes a first reflecting portion and a second reflecting portion that are separated from each other and reflect light guided through the optical waveguide,
The first reflection unit and the second reflection unit are configured by a diffraction grating,
The light-emitting device according to claim 2, wherein the diffraction grating is formed by a concavo-convex structure periodically provided in the second cladding layer. R ₁ R ₂ exp (g-α) L <1
The light-emitting device according to claim 3, wherein:
However, R ₁ is the reflectivity of the first reflector with respect to the cavity inside the guiding light between said second reflecting portion and the first reflection portion of the optical waveguide,
R ₂ is the reflectivity of the second reflecting portion with respect to the light guided inside the resonator,
g is the gain of light guided inside the resonator,
α is an internal loss of light guided through the resonator,
L is the resonator length of the resonator. The resonator includes a diffraction grating formed by a concavo-convex structure periodically provided in the second cladding layer,
The concavo-convex structure is provided from one end of the resonator to the other end of the resonator as viewed from the stacking direction of the active layer and the first cladding layer. 2. The light emitting device according to 2. κL <0.1
The light emitting device according to claim 5, wherein:
Where κ is the coupling coefficient between light traveling in one direction and light traveling in the opposite direction in the resonator,
L is the resonator length of the resonator.   The light emitting device according to claim 5, wherein the resonator has two resonance wavelengths different from each other.   The light emitting device according to claim 1, wherein a Q value of the resonator is less than 1000.   The light-emitting device according to claim 1, wherein the optical waveguide includes a plurality of the resonators. The resonance wavelength of the plurality of resonators is different from each other.
The light emitting device according to 1.   11. The light emitting device according to claim 9, wherein the plurality of resonators are provided symmetrically with respect to a center of the optical waveguide when viewed from a stacking direction of the active layer and the first cladding layer. apparatus.   The light emitting device according to claim 1, wherein the resonator includes a center of the optical waveguide. The optical waveguide has a first light emitting surface and a second light emitting surface for emitting light,
The said optical waveguide is extended in the direction inclined with respect to the normal line of the said 1st light-projection surface and the said 2nd light-projection surface, The any one of Claim 1 thru | or 12 characterized by the above-mentioned. The light-emitting device of description. A light emitting device according to any one of claims 1 to 13,
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 a projector.