JP2004158505A - Surface emitting laser, method of manufacturing same and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface emitting laser which has a large aperture, is capable of outputting a high power stably in a single mode, and reducing a threshold current, and to provide an electronic apparatus equipped with the same and a method of manufacturing the same. <P>SOLUTION: A second region whose effective refractive index is slightly different from the refractive index of a first region is formed so as to surround the first region in the direction of optical resonance, and an electrode used for injecting a current into the first region and an insulator for stopping a current from entering the second region are formed. By this setup, laser rays of a higher order in a lateral mode are never guided through the first region, and laser rays of a single mode are trapped and guided in the first region, so that the surface emitting laser is capable of outputting a high power stably in a single mode, and reducing a threshold current even though laser rays of a lateral mode are emitted as a laser beam of a high power due to a large aperture. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surface emitting laser used as, for example, a vertical cavity type, an electronic device including the surface emitting laser, and a method of manufacturing the surface emitting laser.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a surface emitting laser, for example, a vertical cavity surface emitting semiconductor laser (hereinafter, referred to as “VCSEL” (Vertical Cavity Surface Emitting Laser)), a current is well narrowed down by an oxidation confinement method or the like and the current is injected into an active layer to reduce the threshold. The current was reduced.
[0003]
[Problems to be solved by the invention]
The present inventors provide at least the active layer with a region surrounding the oscillation region and having a refractive index slightly smaller than the refractive index of the oscillation region, thereby unifying the transverse mode of the laser beam emitted while having a large output. Have proposed a VCSEL that can do this.
[0004]
However, there is a problem that, for example, an oxide constriction method for reducing the threshold current cannot be used because the refractive index changes greatly.
[0005]
The present invention has been made to solve such a problem, and a surface emitting laser capable of reducing a threshold current to a stable single mode with a high output by a large aperture, and a surface emitting laser thereof. It is an object of the present invention to provide an electronic device including a laser and a method for manufacturing the surface emitting laser.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a surface emitting laser according to a main aspect of the present invention surrounds a first region having a first refractive index and the first region along a light resonance direction. An active layer having a second region having an effective refractive index different from the refractive index of 1 and having a slight second refractive index, and an electrode for injecting a current into the first region; And an insulator for preventing current from entering the second region.
[0007]
Here, the effective refractive index (or effective refractive index) is a uniform refractive index when the optical characteristics are approximated by replacing a region having a non-uniform refractive index with a region having a uniform refractive index. For example, it refers to the refractive index of a region where holes are provided in the active layer as the region.
[0008]
In the present invention, the first region is surrounded along the resonance direction of light, and the second region is formed such that the difference between the refractive index of the first region and the effective refractive index is small. Since an electrode for injecting a current is provided in the first region and an insulator for preventing the current from entering the second region is formed, light of a higher-order transverse mode is guided through the first region. Instead, the single mode light is confined in the first region and guided, and the transverse mode emitted as laser light is unified despite the high output due to the large aperture, and the threshold current is also reduced. Can be achieved.
[0009]
According to one embodiment of the present invention, the insulator is formed between the second region and the electrode. Thereby, a laser beam with a single high-power transverse mode is emitted from the emission port, and the effect of the current on the oscillation region is formed by forming, for example, an insulator as an insulating layer so as to cover the second region. And the threshold current can be reduced.
[0010]
According to one embodiment of the present invention, the electrode is formed in a ring shape surrounding the emission port of the laser light oscillated by the first region so as to be in contact with the first region. And Thereby, a high-output laser beam with a single transverse mode is emitted from the emission port inside the electrode formed to be in contact with the first region in a ring shape, and the oscillation region of the laser light is most emitted. Can be injected at a location close to the above, so that the current can be more effectively injected into the oscillation region.
[0011]
According to one embodiment of the present invention, the insulator is formed using polyimide or photoresist. Thereby, an insulator can be easily formed.
[0012]
According to one embodiment of the present invention, the second region is formed by forming a plurality of holes in the member of the first region. Thus, while reducing the threshold current, for example, by adjusting the size and the number of air holes having a refractive index of 1 in the medium in the first region, it is possible to easily adjust the medium to be slightly smaller than the first refractive index. Effective refractive index can be obtained.
[0013]
According to one embodiment of the present invention, the holes are formed so as to penetrate the active layer in the resonance direction. Thus, while reducing the threshold current, the first region is surrounded along the resonance direction of light generated by the first region, and the effective refractive index is slightly different from the refractive index of the first region. The second region, which is different from the first region, can be easily formed by, for example, etching or the like, so that the manufacturing cost can be reduced.
[0014]
According to one embodiment of the present invention, the holes are sealed. Accordingly, it is possible to prevent impurities such as dust from adhering to the inner wall of the hole, and prevent deterioration of the surface emitting laser.
[0015]
According to one embodiment of the present invention, the hole is formed by the first refractive index and the second refractive index, the oscillation frequency of the laser light oscillated by the first region, and the resonance of the first region. It is characterized in that the normalized frequency obtained by using the radius when a section orthogonal to the direction is a circular section as a parameter is larger than 0.6 and smaller than 2.405. Accordingly, while reducing the threshold current, the laser light is confined in the first region which is the oscillation region, and the transverse mode of the emitted laser light can be unified.
[0016]
Here, the normalized frequency (v) is, for example, the first refractive index is n₁, The second refractive index is n₂V = (2πa / λ) · (n) where each parameter is a where a is a radius when a section orthogonal to the resonance direction of the first region is a circular section.₁ ²-N₂ ²)^1/2  Say.
[0017]
According to one embodiment of the present invention, the plurality of holes surrounding the first region closest to the first region are each an average value of a distance between hole centers of the respective holes._aveAnd the oscillation wavelength λ_ave/ Λ is greater than 2. Thereby, the innermost hole row (which has the largest effect on the light to be guided) (a plurality of holes that are closest to the first region where the laser light is oscillated and the holes 11 are not formed). 11)_aveSince / λ is larger than 2, the threshold current is reduced while the laser is emitted from a direction in which the transverse mode of the emitted laser beam cannot be unified in a conventional oxide confinement VCSEL. Even when the first region has a high output of which the diameter is four times or more of λ, the transverse mode of the emitted laser light can be unified.
[0018]
According to one embodiment of the present invention, the plurality of holes that surround the hole closest to the first region are an average value of a diameter of a circle corresponding to an area of each of the plurality of holes. d_aveAnd the average value of the distance between the hole centers Λ_aveRatio d_ave/ Λ_aveIs larger than 0.016 and smaller than 0.2. Accordingly, the innermost hole row having the largest effect on the guided light, the ratio d_ave/ Λ_aveIs larger than 0.016 and smaller than 0.2. Therefore, while reducing the threshold current, the laser light is confined in the first region which becomes the oscillation region in, for example, an AlGaAs-based or InGaAsP-based VCSEL. This makes it possible to unify the transverse mode of the laser beam.
[0019]
According to one embodiment of the present invention, the plurality of holes that surround the hole closest to the first region are an average value of a diameter of a circle corresponding to an area of each of the plurality of holes. d_aveAnd the average value of the distance between the hole centers Λ_aveRatio d_ave/ Λ_aveIs larger than 0.03 and smaller than 0.23. Accordingly, the innermost hole row having the largest effect on the guided light, the ratio d_ave/ Λ_aveIs larger than 0.03 and smaller than 0.23, the laser light is confined in the first region which becomes the oscillation region in, for example, a GaN-based VCSEL while the threshold current is reduced. The transverse mode of light can be unified.
[0020]
According to one embodiment of the present invention, the holes are arranged in a triangular lattice shape such that the centers of the nearest holes become equilateral triangles, and the distance 空 between the centers of the holes and the oscillation wavelength The ratio Λ / λ to λ is greater than 2. As a result, since よ り 大 き い / λ is greater than 2, while reducing the threshold current, for example, in a conventional oxidized confinement type VCSEL, the resonance of light is such that the transverse mode of the emitted laser light cannot be unified. Even if the first region viewed from the direction has a high output whose diameter of the first region is 4 times or more of λ, it can act on light guided in the entire second region, so that the transverse mode of the emitted laser light can be reduced. It can be unified.
[0021]
According to one embodiment of the present invention, the hole has a ratio d / Λ between a diameter d of a circle corresponding to the area of the hole and the distance Λ between the centers of the holes greater than 0.016 and 0%. .2. Accordingly, if a plurality of holes satisfying the condition that d / Λ is larger than 0.016 and smaller than 0.2 are regularly formed, the holes can act on light guided in the entire second region. For example, while reducing the current, the laser light can be confined in the first region, which is a more oscillation region in an AlGaAs-based or InGaAsP-based VCSEL, and the transverse mode of the emitted laser light can be unified.
[0022]
According to one embodiment of the present invention, the hole has a ratio d / Λ of a diameter d of a circle corresponding to an area of the hole to the center distance 間 of the hole larger than 0.03 and 0 .23. Accordingly, if a plurality of holes satisfying the condition that d / Λ is larger than 0.03 and smaller than 0.23 are regularly formed, the holes can act on light guided in the entire second region. For example, while reducing the current, the laser light can be confined in the first region that becomes a more oscillating region in, for example, a GaN-based VCSEL, and the transverse mode of the emitted laser light can be unified.
[0023]
An electronic device according to another aspect of the present invention surrounds a first region having a first refractive index and the first region along a resonance direction of light, and the first refractive index is effective. An active layer having a second region having a different refractive index and having a slight difference in the second refractive index, an electrode for injecting a current into the first region, and a second region. A surface-emitting laser comprising: an insulator for preventing current from entering.
[0024]
In the present invention, the first region having the first refractive index and the first region surrounding the first region along the resonance direction of light have an effective refractive index different from the first refractive index, and An active layer having a second region having a second refractive index with a small difference, an electrode for injecting a current into the first region, and an insulator for preventing a current from entering the second region. Since the surface emitting laser is provided, it is possible to unify the transverse mode with a high-power laser beam with a large diameter and to reduce the threshold current, for example, it is possible to write at a high rotation speed and a high transfer speed of an optical disk. Become.
[0025]
According to another aspect of the present invention, there is provided a method for manufacturing a surface emitting laser, comprising: a first region having a first refractive index; and the first region surrounding the first region along a light resonance direction. Forming an active layer having a second region in which holes are pierced in the resonance direction so that the effective refractive index differs from the effective refractive index, and the difference has a slight second refractive index; Immediately after the step of forming the active layer is completed, a step of forming an insulator covering the opening of the hole and preventing current from entering the second region; and supplying a current to the first region. Forming an electrode to be implanted.
[0026]
In the present invention, the first region having the first refractive index and the first region surrounding the first region along the resonance direction of light have an effective refractive index different from the first refractive index, and Forming an active layer having a second region in which holes are made to penetrate in the resonance direction so that the difference has a small second refractive index; A step of forming an insulator covering the opening and preventing current from entering the second region, and a step of forming an electrode for injecting current into the first region. Thus, a surface emitting laser that can stably confine laser light, can easily unify the transverse mode of laser light even at high output, and can reduce the threshold current can be manufactured.
[0027]
In addition, immediately after the step of forming the active layer is completed, a step of forming an insulator that covers the opening of the hole and prevents current from entering the second region is provided. Impurities can be prevented from being attached, and deterioration of the surface emitting laser can be prevented.
[0028]
According to one embodiment of the present invention, the step of forming the insulator includes forming the insulator using polyimide or photoresist as the insulator. As a result, the opening can be easily covered, and the manufacturing cost can be reduced.
[0029]
According to one embodiment of the present invention, the step of forming the electrode is such that the electrode is in contact with the first region in a ring shape surrounding an emission port of laser light oscillated by the first region. It is characterized by being formed. Thereby, for example, a laser beam having a single high-power transverse mode is emitted from the emission port inside the electrode formed so that the contact area with the cap layer is formed in a ring shape, and the laser light is most emitted. Since a current can be injected near the oscillation region, a surface emitting laser capable of further reducing the threshold current can be manufactured.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the embodiment, an AlGaAs system used in a VCSEL (vertical cavity surface emitting semiconductor laser) having an oscillation wavelength of 850 nm will be mainly described as an example of a surface emitting laser, but the present invention is not limited to this. is not.
[0031]
In addition, the size of each part and the number of holes in the drawings below are shown for convenience of description, do not represent actual dimensions and numbers, and do not necessarily match in each drawing.
[0032]
FIG. 1 is a schematic perspective view of a VCSEL according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view in the AA ′ direction of FIG. 1, and FIG. FIG. 4 is a schematic perspective view of the mesa structure of the VCSEL, FIG. 5 is an explanatory view of the electrode contact region viewed from above by removing the polyimide or photoresist of FIG. 4, and FIG. FIG. 7 is a graph illustrating a boundary condition between a higher-order mode and a higher-order mode, and FIG. 7 is a graph illustrating a boundary condition between a GaN-based single mode and a higher-order mode.
[0033]
As shown in FIGS. 1 and 2, a VCSEL 1 is a substrate 2 formed of, for example, GaAs, which is a seed crystal for crystal growth, and a semiconductor multilayer for crystal feedback grown on the substrate 2 and having an active layer or the like interposed therebetween. A lower DBR mirror 3a formed by a combination of, for example, an AlGaAs layer and an AlAs layer on the substrate side of the film DBR (Distributed Bragg Reflector) mirror 3, and a pair of, for example, AlGaAs that is crystal-grown on the lower DBR mirror 3a and sandwiches the active layer. The lower cladding layer 4a on the substrate side of the cladding layer 4 formed from the above, an active layer 5 formed by a combination of, for example, an AlGaAs layer and a GaAs layer which generates light sandwiched between the cladding layers 4, and the active layer 5 Upper cladding layer 4b which is crystal-grown in For example, an upper DBR mirror 3b formed by a combination of an AlGaAs layer and an AlAs layer, and a cap layer 6 for growing a crystal on the upper DBR mirror 3b and lowering a contact resistance between an upper electrode and a semiconductor, which will be described later. An insulating layer 7 covering a part of the cap layer 6 so that the electrode can efficiently inject a current into the cap layer 6, and an upper electrode 8 formed on the insulating layer 7 and a part of the cap layer 6 by vapor deposition or the like; A cap layer 6, an insulating layer 7, and an upper electrode for emitting laser light from a lower electrode 9 and an upper DBR mirror 3b formed by vapor deposition or the like on the side of the substrate 2 opposite to the crystal growth layer (for example, the lower DBR mirror 3a). 8 is provided with an emission port 10 and the like.
[0034]
Here, the substrate 2 is for crystal growth of the semiconductor multi-layer film DBR mirror 3, the clad layer 4, and the like, and is for stacking while maintaining a regular lattice and forming atoms firmly.
[0035]
Further, the lower DBR mirror 3a is a semiconductor in which the property of forming a reflecting mirror by alternately stacking films having different refractive indices is applied to a semiconductor. As described above, for example, an AlGaAs layer and an AlAs layer are alternately stacked and the active layer 5 is formed. It reflects the generated light.
[0036]
The film thickness at which the reflectance is the maximum is such that the relationship between the wavelength λ and the refractive index n is λ / 4n, and the entire thickness is, for example, approximately 3.9 μm.
[0037]
Similarly, the upper DBR mirror 3b is, for example, an alternate stack of AlGaAs layers and AlAs layers and reflects light generated in the active layer 5, but unlike the lower DBR mirror 3a, the overall thickness is approximately 2 The number of pairs of the AlGaAs layer and the AlAs layer is made smaller than that of the lower DBR mirror 3a, so that the laser beam can be emitted from the emission port 10 provided on the upper DBR mirror 3b side. .
[0038]
Further, the cladding layer 4 is formed of, for example, AlGaAs, and is laminated with its lower cladding layer 4a and upper cladding layer 4b so as to sandwich the active layer 5, as shown in FIG. .
[0039]
The active layer 5 has a multiple quantum well structure formed by, for example, a combination of an AlGaAs layer and a GaAs layer. The active layer 5, the lower cladding layer 4a, and the upper cladding layer 4b have a total thickness of about 0.1 mm. It is formed to 3 μm.
[0040]
Here, for example, as shown in FIG. 2, holes 11 form a light resonance direction from the cap layer 6 toward the substrate 2, from the cap layer 6, the upper DBR mirror 3 b, the upper clad layer 4 b, the active layer 5 and the lower clad layer 4 a. The hole 11 is also formed in the upper part of the lower DBR mirror 3a on the side of the lower cladding layer 4a along the resonance direction of light. The total length in the direction is, for example, 4 μm. As a result, the generated light is affected by the holes 11 many times due to reflection, and the effect of suppressing the higher-order mode by the holes 11 can be sufficiently obtained at a longer distance.
[0041]
Further, a region from the upper DBR mirror 3b to the lower DBR mirror 3a where light is reflected, resonated, amplified and oscillated with the cap layer 6 is defined as a first region, and a region where the holes 11 are formed is defined as a second region. Then, as shown in FIG. 2 and, for example, FIG. 3 which is an explanatory view of the active layer 5 as viewed from above, the second region has a hole 11 penetrated so as to surround the first region along the light resonance direction. Is formed.
[0042]
Further, the arrangement of the holes 11 is regularly arranged in a triangular lattice such that the centers of the nearest holes become an equilateral triangle when viewed from above, as shown in FIG. 3, for example. The shape of the hole 11 is formed as a circle of the same size.
[0043]
In addition, as shown in FIG. 3, a region from which only one hole is removed from the triangular lattice is a first region, and laser light oscillates from that region. Assuming that the first region is a circle, its diameter is approximately 2Λ (more precisely, 2 空 -d) as shown in FIG.
[0044]
The holes 11 are formed such that the ratio Λ / λ between the distance Λ between the centers of the holes and the oscillation wavelength λ is larger than 2, and the diameter d of the circle of the holes 11 and each of the holes 11 The holes are formed such that the ratio of the distance between the holes to the center Λ is larger than 0.016 and smaller than 0.2. As a result, a laser that is emitted even with a high output power in which the diameter of the first region is four times or more λ is such that the transverse mode of the emitted laser light cannot be unified in the conventional oxide confinement type VCSEL. The transverse mode of light can be unified.
[0045]
For example, in a VCSEL 1 using GaAs for the active layer 5 and having an oscillation wavelength of 850 nm, Λ / λ is set to 10.58 and d / よ う is set so that the diameter of the first region is 17.1 μm, which is 10 times or more the oscillation wavelength. The diameter d of all the holes 11 is set to 0.9 μm, and the distance 空 between all the holes is set to 9 μm so as to be 0.1. As a result, the laser light is confined in the first region serving as the oscillation region, and the transverse mode can be unified while having a high output.
[0046]
Further, the diameter d of the hole 11 of 0.9 μm is a dimension that can be sufficiently patterned by an ultraviolet exposure apparatus which is widely used in semiconductor photolithography and has excellent mass productivity, and has a single transverse mode determined by an effective refractive index method. Since a value slightly smaller than the value of d / Λ, which is the upper limit of, is selected, it is possible to absorb a certain degree of dimensional change during the formation of holes.
[0047]
The shape of the holes 11 is not limited to a circle, and may be, for example, a rhombus other than a circle. In this case, the diameter of a circle corresponding to the area of the diamond is d. The holes 11 are filled with, for example, air.
[0048]
In addition, for example, as shown in FIG. 4, a second region in which holes 11 are formed and a second region thereof, extending over the cap layer 6, the upper DBR mirror 3b, the upper cladding layer 4b, the active layer 5, and the lower cladding layer 4a. A mesa 12 having a diameter of approximately 150 μm is formed so as to include the first region surrounded by the circle.
[0049]
Further, the insulating layer 7 is made of polyimide or photoresist so as to leave a portion where the emission port 10 and the upper electrode 8 are in contact with the cap layer 6 as shown in FIGS. 12 and is formed so as to bury the periphery of the mesa 12 so that the upper surface is slightly flattened. As a result, the current can be efficiently confined and impurities such as dust can be prevented from reaching the inner wall of the hole 11.
[0050]
The upper electrode 8 and the lower electrode 9 are made of a material centered on Au, which can be easily alloyed with GaAs or the like. The upper electrode 8 is formed on the entire upper surface of the insulating layer 7 as shown in FIGS. In an opening formed above the insulating layer 7 on the first region, for example, an outer diameter is approximately 14 μm, and an inner diameter is approximately 10 μm. The thickness is approximately 1 μm.
[0051]
As a result, as shown in FIG. 5, the upper electrode 8 comes into contact with the cap layer 6 only in a ring-shaped region having, for example, an outer diameter of approximately 14 μm and an inner diameter of approximately 10 μm. Injection can reduce the threshold current.
[0052]
Here, as shown in FIG. 5, when a ring-shaped region where the upper electrode 8 contacts the cap layer 6 is defined as an electrode contact region, if the electrode contact region is too narrow, the resistance increases. The second region in which is formed is too far from the oscillation region, and the effect of confining the laser beam and unifying the transverse mode cannot be sufficiently achieved. In the meantime, as an example of a suitable electrode contact area, as described above, contact is made only in a ring-shaped area having an outer diameter of about 14 μm and an inner diameter of about 10 μm.
[0053]
Further, the emission port 10 is formed to have a diameter of 10 μm by removing the cap layer 6. When a predetermined current is injected into the VCSEL 1 through the upper electrode 8 and the lower electrode 9, the laser light is emitted from the emission port 10. Will be done.
[0054]
Here, the holes 11 are formed such that the ratio d / Λ between the diameter d of the circle and the distance Λ between the centers of the holes is larger than 0.016 and smaller than 0.2. The same applies to InGaAsP-based materials used in VCSELs having an oscillation wavelength of 1550 nm other than AlGaAs, which is a material used in VCSELs having an oscillation wavelength of 850 nm.
[0055]
However, in a GaN system or the like, which is a material system used in a VCSEL having an oscillation wavelength of 400 nm, the refractive index is considerably small, so that the ratio d / Λ between the diameter d of the holes and the distance 空 between the centers of the holes. Is preferably larger than 0.03 and smaller than 0.23. As a result, even in a GaN system or the like, which is a material system used in a VCSEL having an oscillation wavelength of 400 nm, laser light is confined in the first region serving as an oscillation region, and the transverse mode can be unified.
[0056]
Next, the operation of the VCSEL 1 configured as described above will be briefly described.
[0057]
First, when a predetermined current is injected into the upper electrode 8, the current is regulated by the insulating layer 7, and only from the contact area with the ring-shaped cap layer 6 on the first area, the cap layer 6 and the like are formed. Will be entered. As a result, the current can be efficiently injected into the oscillation region, and the threshold current of the VCSEL 1 can be reduced.
[0058]
Light is generated in the active layer 5 by the efficiently injected current, but holes are formed in an in-plane direction (lateral direction, XZ plane direction in FIGS. 1 and 2) perpendicular to the light resonance direction. Since the effective refractive index of the second region is slightly smaller in the first region, which is a region where no holes are present, and in the second region in which holes are formed outside the first region, the laser is included in the first region. Light will be confined.
[0059]
That is, the effective refractive index of the second region is slightly lower than that of the first region by sparsely arranging the holes filled with air in the second region, and the in-plane direction (FIG. 1 and the XZ plane direction in FIG. 2).
[0060]
As a result, the light generated in the first region has a small difference in the refractive index even though the width of the waveguide is wide, so that the light in the single transverse mode is near the boundary between the first region and the second region. The light is guided as a whole in the light resonance direction (Y direction in FIGS. 1 and 2), is reflected by the semiconductor multilayer DBR mirror 3 sandwiching the active layer 5 and the like up and down, and resonates. The light is amplified and oscillated as a laser beam, and is emitted from the emission port 10.
[0061]
Further, as described above, the difference between the effective refractive index of the second region realized by the arrangement of the holes and the refractive index of the first region is very small, and this structure makes it possible to stably weaken the confinement force. Therefore, even when the diameter of the first region viewed from the resonance direction is large, which cannot be achieved by means of oxidation constriction or the like having a large refractive index difference, single transverse mode laser light can be oscillated.
[0062]
Next, how the dimensions of the diameter d of the hole circle and the distance 中心 between the hole centers of the respective holes at a predetermined oscillation wavelength λ will be specifically described based on the operation of the VCSEL 1 will be described. I do.
[0063]
Regarding the operation of light when the difference between the refractive index of the first region and the second effective refractive index is small, similarly, the difference between the refractive index of the first region and the second refractive index is small. The operation of light in confining light in the core of a step index optical fiber can be used.
[0064]
As a value representing the structural characteristics of the step index optical fiber, a normalized frequency v = (2πa / λ) · (n_core ²-N_clad ²)^1/2  (Λ: wavelength, a: core radius, n_core  : Core refractive index, n_clad  : Cladding refractive index), and the light confinement efficiency of the core depends on this v. When v is 0.6, the light confinement efficiency becomes substantially zero, and the function as the clad disappears.
[0065]
In addition, the unification of the transverse mode of the step index type optical fiber requires that v be smaller than 2.405, and the above points can be applied to the VCSEL1.
[0066]
Therefore, when the normalized frequency v of the VCSEL 1 is larger than 0.6 and smaller than 2.405, the laser light is confined in the first region, which is the oscillation region, and the transverse mode of the emitted laser light is unified. It is a condition that can be done.
[0067]
Note that the normalized frequency v of the VCSEL 1 is the radius of the circle when the surface orthogonal to the resonance direction of light in the first region is a circle in the equation of the normalized frequency v of the step index optical fiber, The core refractive index can be derived as the refractive index of the first region, and the cladding refractive index can be derived as the effective refractive index of the second region.
[0068]
Further, the combination of the oscillation wavelength λ, the diameter d of the hole circle, and the distance 中心 between the centers of the holes, which satisfy the above-mentioned normalized frequency condition, is specifically shown in FIG. 6 by the effective refractive index method. Asked as shown.
[0069]
The upper curve group B shown in FIG. 6 is a line that gives v = 2.405 for AlGaAs having a different Al composition, and the predetermined oscillation wavelength λ, diameter d, and hole center distance 空 below this line Thus, the transverse mode can be unified.
[0070]
The lower curve group C in FIG. 6 is a line giving v = 0.6 for AlGaAs having a different Al composition, and a predetermined oscillation wavelength λ, diameter d, and hole center distance よ り above this line. With the dimensions described above, laser light can be confined in the first region.
[0071]
Here, each curve of the curve groups B and C is Al_XGa_1-XIt is a curve when x of As is 1, 0.5, 0, the vertical axis is the ratio d / Λ of the diameter d of the hole 11 and the distance 間 between the hole centers, and the horizontal axis is the distance between the hole centers. The ratio of 発 振 to the oscillation wavelength λ is Λ / λ (the vertical and horizontal axes are the same in FIG. 7 described later).
[0072]
Therefore, unless the hole 11 is formed in the second region, the ratio Λ / λ between the oscillation wavelength λ and the hole center distance な る, which has a large diameter, where the transverse mode of the laser beam cannot be unified, is larger than 2. In order to satisfy both the conditions of confining the laser light in the first region and unifying the transverse mode of the laser light, the diameter d of the hole circle and the distance between the hole centers of the respective holes Λ Must be greater than 0.016 and less than 0.2.
[0073]
Note that the curve groups B and C in FIG. 6 are based on the refractive index (having a value between 3.0 and 3.6 depending on the composition) of AlGaAs which is a material system used in the VCSEL having an oscillation wavelength of 850 nm as described above. The same applies to the InGaAsP system (refractive index: 3.0 to 3.4) which is a material system used in a VCSEL having an oscillation wavelength of 1550 nm.
[0074]
However, a GaN-based material (refractive index: 2.0 to 2.4) or the like, which is a material used in a VCSEL having an oscillation wavelength of 400 nm, has a considerably small refractive index. Become like
[0075]
That is, the two upper curves shown in FIG. 7 (curve D indicates GaN and curve E indicates AlN) are lines that give v = 2.405 for the GaN system, and a predetermined oscillation below this line The transverse mode can be unified with the wavelength λ, the diameter d, and the distance Λ between the centers of the holes.
[0076]
The lower two curves in FIG. 7 (curve F represents GaN and curve G represents AlN) are lines that give v = 0.6 for the GaN system, and a predetermined oscillation above this line is given. The laser beam can be confined in the first region by the dimensions of the wavelength λ, the diameter d, and the distance 中心 between the centers of the holes.
[0077]
Therefore, in a GaN-based material (refractive index: 2.0 to 2.4) or the like, which is a material system used in a VCSEL having an oscillation wavelength of 400 nm, unless the holes 11 are formed in the second region, the transverse mode of the laser beam is unified. In the entire region where the ratio Λ / λ between the oscillation wavelength λ and the hole center distance 中心, which is a large diameter that cannot be achieved, is larger than 2, the confinement of the laser light in the first region and the unification of the transverse mode of the laser light In order to satisfy both of the conditions, as shown in FIG. 7, the ratio d / Λ between the diameter d of the hole circle and the distance Λ between the centers of the holes is greater than 0.03 and 0.23. It will be necessary to form it so as to be smaller.
[0078]
Next, a method of manufacturing the VCSEL 1 configured as described above will be described.
[0079]
FIG. 8 is a flowchart of the VCSEL manufacturing method according to the present embodiment, FIG. 9 is an explanatory view of a crystal growth step in the VCSEL manufacturing process according to the present embodiment, and FIG. 10 is a hole next to FIG. FIG. 11 is an explanatory view of a hole confining step which is the next step of FIG. 10, FIG. 12 is an explanatory view of a mesa forming step which is the next step of FIG. 11, and FIG. FIG. 14 is an explanatory view of an insulating layer forming step which is the next step after FIG. 12, FIG. 14 is an explanatory view of an upper electrode forming step which is the next step of FIG. 13, and FIG. 15 is a top view of the upper electrode of FIG. FIG. 16 is an explanatory view of a step of forming an emission port, which is the next step of FIG. 14, and FIG. 17 is a step of forming a lower electrode, which is the next step of FIG.
[0080]
First, as shown in FIG. 9, for example, a GaAs substrate 2 having a thickness L of approximately 525 μm, which is a sufficiently washed seed crystal, is prepared, and a lower DBR mirror 3a formed on the GaAs substrate 2 by combining an AlGaAs layer and an AlAs layer. Is grown by, for example, MOCVD (Metal Organic Chemical Vapor Deposition), which is a growth method utilizing a chemical reaction, and the thickness K is formed to be approximately 3.9 μm. Similarly, a lower cladding layer 4a formed of AlGaAs is formed on the lower DBR mirror 3a, an active layer 5 formed of an AlGaAs layer and a GaAs layer is formed thereon, and an upper cladding formed of AlGaAs is further formed thereon. A layer 4b, an upper DBR mirror 3b having a thickness I of about 2.6 μm formed by a combination of an AlGaAs layer and an AlAs layer, and a cap layer 6 having a thickness H of about 0.2 μm thereon. It is grown (ST101). The overall thickness J of the lower cladding layer 4a, the active layer 5, and the upper cladding layer 4b is, for example, approximately 0.3 μm.
[0081]
Next, as shown in FIGS. 3 and 10, for example, patterning is performed with a photoresist. From the cap layer 6 to the upper part of the lower DBR mirror 3a, the diameter d is about 0.9 μm and the distance 間 between the centers of the holes is about 9 μm. The circular holes 11 are formed by regularly arranging eight holes on one side in a triangular lattice such that the centers of the nearest holes are equilateral triangles (although four holes are shown in FIG. 3). It is formed to have a depth M of about 4 μm by a technique of reactive ion etching (RIE) using a Cl-based gas (ST102).
[0082]
Immediately after the formation of the holes 11, as shown in FIG. 11, for example, polyimide or a photoresist 13 a is spin-coated on the upper surface of the cap layer 6 in which the holes 11 are formed to a thickness of about 0.5 μm. The opening formed on the upper surface of the cap layer 6 is closed by the hole 11, and the polyimide or the photoresist 13a is hard-cured and hardened, and the polyimide or the photoresist 13a closing the hole 11 is not removed in the subsequent steps. (ST103).
[0083]
As a result, the holes 11 formed by RIE are immediately closed, so that it is possible to prevent impurities such as dust from adhering to the inner walls of the holes 11 and prevent the VCSEL 1 from deteriorating. The viscosity of the photoresist and the like and the spin coating conditions are selected so that the photoresist and the like do not enter the holes 11 as much as possible.
[0084]
Next, patterning is performed again with, for example, a photoresist, and the outer peripheral portion of the second region where the holes 11 are formed is etched by Cl-based gas RIE as shown in FIG. 12 to form the mesa 12 (ST104). The etching depth N is, for example, about 3.6 μm so as to reach the surface of the lower DBR mirror 3a, and the diameter of the mesa 12 formed by etching is, for example, about 150 μm.
[0085]
Again, polyimide or photoresist 13b is spin-coated so as to cover the mesa 12 formed in ST104 and bury the periphery of the mesa 12, to make the steps of the mesa 12 substantially flat, and then to perform hard curing to perform polyimide or photoresist. 13b is cured.
[0086]
Further, for example, patterning and etching is performed by using a photoresist, and a polyimide or photoresist 13a and 13b on the upper surface of the cap layer 6 is formed in a circular shape so that the diameter (hereinafter, referred to as “constriction diameter”) becomes 14 μm in the first region. Is formed as shown in FIG.
[0087]
The portion formed by the polyimide or the photoresists 13a and 13b narrows down the current from the upper electrode 8 formed in the next step and efficiently injects the current into the first region which is the oscillation region. (ST105).
[0088]
Next, an electrode material, for example, a material centering on Au, which can be easily alloyed with GaAs, is deposited on the entire upper surface of the insulating layer 7 and the cap layer 6 formed in ST105, and patterned with a photoresist thereon. Then, a circular photoresist window having a diameter of, for example, 10 μm is formed in the upper opening (constriction diameter) of the insulating layer 7.
[0089]
Thereafter, as shown in FIGS. 14 and 15, the electrode material outside the photoresist (the portion of the circular window having a diameter of 10 μm) is removed by ion beam etching or the like, the photoresist is peeled off, and the insulating layer on the first region is removed. The upper electrode 8 is formed such that a circular window having a diameter of 10 μm is formed in the upper opening (constriction diameter) of the substrate 7 and the thickness is about 1 μm (ST106).
[0090]
Thereby, as shown in FIGS. 14 and 15, the upper electrode 8 comes into contact with the cap layer 6 only in a ring-shaped region (electrode contact region) having an outer diameter of about 14 μm and an inner diameter of about 10 μm, for example. The current can be efficiently injected into the oscillation region, and the threshold current can be reduced.
[0091]
Here, the above-described upper electrode 8 is formed by an etching method, but may be formed by a lift-off method. The lift-off method is, for example, a method of forming an inverted pattern of a desired shape with a photoresist, forming an electrode material, and removing the photoresist and the electrodes on the photoresist with a solvent to obtain a desired pattern. The process is simpler than.
[0092]
Next, as shown in FIG. 16, using the upper electrode 8 formed in ST106 as a mask, the cap layer 6 is partially removed by wet etching in accordance with the circular window of the upper electrode 8, thereby forming the laser beam emission port 10. (ST107). The opening diameter of the cap layer 6 after being removed by the wet etching is, for example, 10 μm and the depth thereof is about 0.2 μm, and ammonia peroxide is used as an etching solution.
[0093]
Further, the substrate 2 is polished from the surface on the side opposite to the lower DBR mirror 3a side (the lower side in FIG. 16) to a thickness of about 100 μm, the polished surface is neatly prepared by etching or the like, and the electrode layer is about 1 μm in thickness. Then, the lower electrode 9 is formed as shown in FIG. 17 (ST108).
[0094]
The lamination structure as a semiconductor laser has been almost completed, but in order to commercialize it as a VCSEL, for example, a step of cleaving a chip for each element, a step of die bonding to a stem (mount with foot), and a step of forming electrodes on the surface It is necessary to perform a step of wire-bonding the stem and the stem, and a step of caps and seals for shielding from outside air.
[0095]
As described above, according to the present embodiment, the first region is surrounded along the resonance direction of light, and the difference between the refractive index of the first region and the effective refractive index becomes small. In addition to the formation of the second region and the formation of an electrode for injecting current into the first region and an insulator for preventing current from entering the second region, the light of the higher-order transverse mode can be transmitted to the first region. The single mode laser light is confined and guided in the first region without being guided through the region, and the transverse mode emitted as the laser light is unified despite its high output due to the large aperture, and its The threshold current can be reduced.
[0096]
Specifically, from the cap layer 6 and the upper DBR mirror 3b to the upper part of the lower DBR mirror 3a, a plurality of holes 11 filled with air penetrating the first region along the light resonance direction are formed. Then, the second region of the cap layer 6 is covered with the insulating layer 7 so that the upper electrode 8 contacts the cap layer 6 only in the ring-shaped region. The desired effective refractive index slightly smaller than the refractive index of the first region can be easily obtained by adjustment, and the transverse mode emitted as the laser beam is a single mode despite the high output due to the large aperture. The threshold current of the VCSEL 1 can be reduced by efficient and efficient current injection.
[0097]
Further, since the upper electrode 8 contacts only in a ring-shaped region having an outer diameter of approximately 14 μm and an inner diameter of approximately 10 μm, for example, the second region in which the resistance is not increased and the holes 11 are formed. Is not too far from the oscillation region, and the transverse mode sufficiently emitted as laser light by the action of the holes 11 can be unified despite the high output due to the large aperture.
[0098]
Furthermore, since the air is filled in the holes 11, the manufacturing cost can be reduced as compared with a case where another material is newly filled.
[0099]
Further, since the formed holes 11 are immediately closed with a photoresist or the like, it is possible to prevent impurities such as dust from adhering to the inner walls of the holes 11 and prevent the VCSEL 1 from deteriorating.
[0100]
Further, a cross section orthogonal to the refractive index of the first region, the effective refractive index of the second region, the oscillation frequency of the laser light oscillated by the first region, and the resonance direction of the first region is defined as a circular cross section. Since the normalized frequency obtained as a parameter with the radius at the time of performing is larger than 0.6 and smaller than 2.405, the laser light is emitted to the first region which is the oscillation region while reducing the threshold current. Is confined, and the transverse mode of the emitted laser light can be unified.
[0101]
Further, the centers of the nearest holes are regularly arranged in a triangular lattice so as to form an equilateral triangle, and the ratio Λ / λ between the distance 空 between the centers of the holes and the oscillation wavelength λ is larger than 2. Therefore, for example, the diameter of the first region viewed from the resonance direction of the light such that the transverse mode of the emitted laser light cannot be unified in the conventional oxidation confinement type VCSEL is four times or more λ. Thus, the transverse mode of the emitted laser light can be unified while reducing the threshold current.
[0102]
Further, a plurality of holes are formed such that the ratio d / Λ between the diameter d of the circle corresponding to the area of the hole and the distance Λ between the centers of the holes is larger than 0.016 and smaller than 0.2. Since the holes 11 are formed, the laser light is confined in the first region which becomes the oscillation region in the VCSEL 1 of, for example, an AlGaAs or InGaAsP system while the threshold current is reduced, and the transverse mode of the emitted laser light is reduced to a single mode. Can be
[0103]
Further, for example, in the GaN-based VCSEL 1, a plurality of holes 11 are formed so that d / Λ is larger than 0.03 and smaller than 0.23. However, the laser light can be confined in the first region which is the oscillation region, and the transverse mode of the emitted laser light can be further united.
[0104]
Furthermore, in the step of covering the opening of the hole 11, the opening is covered by using polyimide or photoresist for the sealing member, so that the opening can be easily covered, and the manufacturing cost can be reduced.
[0105]
Next, a VCSEL according to a second embodiment of the present invention will be described.
[0106]
FIG. 18 is a view for explaining the arrangement of holes in the VCSEL according to the second embodiment of the present invention, and is an explanatory view of, for example, an active layer viewed from above.
[0107]
The configuration of the VCSEL 101 according to the second embodiment is different from the configuration of the VCSEL 1 according to the first embodiment in which a plurality of holes are regularly arranged at the same size, whereas the configuration is the closest to the first region. The same as the configuration of the first embodiment, except that the plurality of holes surrounding the holes are arranged under a certain condition, and the other holes are the same except that the size and the arrangement are also different. The description of the point is omitted, and the size and arrangement of the holes different from the configuration of the first embodiment will be described below. In the following description, the same components as those described in the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted.
[0108]
In other words, as shown in FIGS. 1 and 2, the VCSEL 101 has a substrate 2 formed of, for example, GaAs, which is a seed crystal for crystal growth, and a crystal grown on the substrate 2 for feedback of light across an active layer and the like. A lower DBR mirror 3a formed by a combination of, for example, an AlGaAs layer and an AlAs layer on the substrate side of the semiconductor multilayer film DBR (Distributed Bragg Reflector) mirror 3, and a pair of crystals which are crystal-grown on the lower DBR mirror 3a and sandwich an active layer. For example, a lower cladding layer 4a on the substrate side of a cladding layer 4 formed of AlGaAs, an active layer 5 formed by a combination of, for example, an AlGaAs layer and a GaAs layer for generating light sandwiched between the cladding layers 4, Upper cladding layer 4b grown on layer 5 and its upper cladding For example, an upper DBR mirror 3b formed by a combination of an AlGaAs layer and an AlAs layer formed by crystal growth on the layer 4b, and a cap layer formed by crystal growth on the upper DBR mirror 3b and lowering a contact resistance between an upper electrode and a semiconductor described later. 6, an insulating layer 7 covering a part of the cap layer 6 so that the upper electrode can efficiently inject a current into the cap layer 6, and an upper part formed on the insulating layer 7 and a part of the cap layer 6 by vapor deposition or the like. A cap layer 6 for emitting laser light from the electrode 8, the lower electrode 9 and the upper DBR mirror 3b formed on the side opposite to the crystal growth layer (for example, the lower DBR mirror 3a) of the substrate 2 by vapor deposition or the like, and an insulating layer 7 and an emission port 10 opened in the upper electrode 8.
[0109]
Here, a region from the upper DBR mirror 3b to the lower DBR mirror 3a where light is reflected, resonated, amplified, and oscillated with the cap layer 6 is defined as a first region, and a region where the holes 11 are formed is defined as a second region. Then, as shown in FIG. 2 and, for example, FIG. 18, which is an explanatory view of the active layer 5 as viewed from above, the second region has a hole penetrating the first region along the light resonance direction. 11 are formed.
[0110]
In addition, the arrangement and shape of the holes 11 are, for example, as shown in FIG. 18, when a laser beam is oscillated when viewed from above, and a plurality of holes 11 surround the first region where the holes 11 are not formed. In the arrangement of the holes 11 (hereinafter referred to as “innermost hole row”), the holes 11 are formed in an array and a shape under a certain condition, and the other holes 11 are different in shape and arrangement of the holes 11. Is formed.
[0111]
However, the effective refractive index of the second region due to all the holes 11 formed in the second region including the holes 11 other than the innermost hole row will be described in the first embodiment of the VCSEL 101. Holes 11 other than the innermost hole row must also be formed so that the standardized frequency v becomes larger than 0.6 and smaller than 2.405.
[0112]
When the first region is a circle when viewed from above, the diameter is the average diameter when the holes 11 are circles in the innermost hole row._aveAs can be seen from FIG. 18, the average center-to-center distance between holes is substantially equal to_aveTwice (exactly 2Λ_ave-D_ave).
[0113]
The constant condition of the arrangement and the shape of the innermost peripheral hole row described above means that the holes 11 of the innermost peripheral hole row are the average distance between the hole centers Λ._aveAnd the oscillation wavelength λ_ave/ Λ is greater than 2, and the average diameter d of the circle of the hole 11_aveAnd the average hole center distance between each hole 同 士_aveRatio d_ave/ Λ_aveIs larger than 0.016 and smaller than 0.2. As a result, the threshold current is reduced even in a high output power in which the diameter of the first region is four times or more λ, such that the transverse mode of the emitted laser beam cannot be unified in the conventional oxidation confinement type VCSEL. It is possible to unify the transverse mode of the emitted laser light while reducing it.
[0114]
For example, in a VCSEL 101 using GaAs for the active layer 5 and having an oscillation wavelength of 850 nm, the average diameter between the center of the innermost hole row is set so that the diameter of the first region is 17.1 μm which is 10 times or more the oscillation wavelength. DistanceΛ_aveAnd the oscillation wavelength λ_ave/ Λ is 10.58, and the average diameter d of the innermost hole row_aveAnd the average hole center distance between each hole 同 士_aveRatio d_ave/ Λ_aveIs 0.1, the average diameter d of the holes 11 in the innermost hole row is_aveIs 0.9 μm, the average distance between hole centers 中心_{a ve}Is 9 μm.
[0115]
As a result, the laser light is confined in the first region serving as the oscillation region while reducing the threshold current, and the transverse mode can be unified while having high output. Needless to say, the normalized frequency v obtained from the effective refractive index of the second region as a whole including the holes 11 having different sizes and arrangements of holes other than the innermost hole row is 0.6. It is assumed that it is formed so as to be larger and smaller than 2.405.
[0116]
The average diameter d of the holes 11 in the innermost hole row_ave0.9 μm is a dimension that can be sufficiently patterned by an ultraviolet exposure apparatus which is widely used in semiconductor photolithography and has excellent mass productivity._ave/ Λ_aveSince a value slightly smaller than the above value is selected, it is possible to absorb a certain degree of dimensional fluctuation during the formation of holes.
[0117]
The holes 11 in the innermost peripheral hole row do not necessarily have to have the same hole diameter d and the distance 中心 between the centers of the holes._aveAnd Λ_aveIs the above condition, d_ave/ Λ_aveShould be larger than 0.016 and smaller than 0.2. The shape of the holes 11 is not limited to a circle, but may be, for example, a rhombus other than a circle. In this case, the diameter of a circle corresponding to the area of the diamond is d. Further, the holes 11 are filled with, for example, air.
[0118]
Further, the holes 11 of the innermost peripheral hole row are formed, for example, by the average diameter d of the circle._aveAnd the average hole center distance between each hole 同 士_aveRatio d_ave/ Λ_aveIs formed so as to be larger than 0.016 and smaller than 0.2. However, other than AlGaAs which is a material system used for a VCSEL having an oscillation wavelength of 850 nm, InGaAsP system which is a material system used for a VCSEL having an oscillation wavelength of 1550 nm and the like are also used. The same is true.
[0119]
However, in the case of a GaN system or the like, which is a material system used in a VCSEL having an oscillation wavelength of 400 nm, since the refractive index is considerably small, the average diameter d of the holes in the innermost hole array is reduced._aveAnd the average hole center distance between each hole 同 士_aveRatio d_ave/ Λ_aveIs preferably larger than 0.03 and smaller than 0.23. As a result, even in a GaN system or the like, which is a material system used in a VCSEL having an oscillation wavelength of 400 nm, the laser light is confined in the first region that is an oscillation region while the threshold current is reduced, and the transverse mode can be unified. .
[0120]
Next, the operation of the VCSEL 101 thus configured will be briefly described.
[0121]
First, when a predetermined current is injected into the upper electrode 8, the current is regulated by the insulating layer 7, and only from the contact area with the ring-shaped cap layer 6 on the first area, the cap layer 6 and the like are formed. Will be entered. As a result, current can be efficiently injected into the oscillation region, and the threshold current of the VCSEL 101 can be reduced.
[0122]
Light is generated in the active layer 5 by the efficiently injected current, but a hole 11 is formed in an in-plane direction (lateral direction, XZ plane direction in FIGS. 1 and 2) orthogonal to the light resonance direction. Since the effective refractive index of the second region is slightly smaller in the first region, which is the non-exposed region, and in the second region of the region in which the holes 11 are formed outside the first region, the first region The laser light is confined inside.
[0123]
That is, by sparsely arranging the holes 11 filled with air in the second region, the effective refractive index of the second region is slightly lower than that of the first region, and the in-plane direction ( It functions as a so-called cladding layer (in the XZ plane direction in FIGS. 1 and 2).
[0124]
As a result, the light generated in the first region is most affected by the holes 11 in the innermost hole row shown in FIG. 18 due to the slight difference in the refractive index even though the width of the waveguide is wide. However, the light of the single transverse mode is totally reflected near the boundary between the first region and the second region, and the light is guided as a whole in the light resonance direction (Y direction in FIGS. The light is reflected by the semiconductor multilayer DBR mirror 3 sandwiching the layer 5 and the like up and down, resonates, is further amplified, oscillates as laser light, and is emitted from the emission port 10.
[0125]
Further, as described above, the difference between the effective refractive index of the second region, which is realized by the formation of the holes, and the refractive index of the first region is extremely small. Since it is obtained stably, even when the diameter of the first region viewed from the resonance direction is large, which cannot be achieved by means such as oxidation constriction having a large difference in refractive index, single transverse mode laser light can be oscillated. .
[0126]
Next, it is necessary to satisfy certain conditions in the holes 11 of the innermost hole row having the largest effect on light guided in the first region. Specifically, at a predetermined oscillation wavelength λ, the average diameter d of the hole circle_ave, The average hole center distance between each hole 空_aveNo_ave/ Λ and d_ave/ Λ_aveHas certain conditions and will be described below. Note that how the certain condition is determined based on the operation of the VCSEL 101 is the same as in the description of the first embodiment, and a description thereof will be omitted.
[0127]
First, when the normalized frequency v of the VCSEL 101 is larger than 0.6 and smaller than 2.405, the laser beam is confined in the first region, which is the oscillation region, and the transverse mode of the emitted laser beam is unified. It is a condition that can be done.
[0128]
Note that the normalized frequency v of the VCSEL 101 is the radius of the circle when the surface orthogonal to the resonance direction of light in the first region is a circle in the equation of the normalized frequency v of the step index optical fiber; The core refractive index can be derived as the refractive index of the first region, and the cladding refractive index can be derived as the effective refractive index of the second region.
[0129]
Further, the oscillation wavelength λ that satisfies the above-described standardized frequency condition, and the average diameter d of the holes 11 in the innermost hole row_aveAnd the average hole center distance between the holes の_aveAre specifically determined by the effective refractive index method as shown in FIG.
[0130]
The upper curve group B shown in FIG. 6 is a line giving v = 2.405 for AlGaAs having a different Al composition, a predetermined oscillation wavelength λ below this line, and Average diameter d_aveAnd average hole center distance 空_aveWith this dimension, the unification of the transverse mode can be further improved.
[0131]
The lower curve group C in FIG. 6 is a line that gives v = 0.6 for AlGaAs having a different Al composition, a predetermined oscillation wavelength λ above this line, and the holes in the innermost hole row. 11 average diameter d_aveAnd average hole center distance 空_aveWith this dimension, light can be more confined in the first region.
[0132]
Here, each curve of the curve groups B and C is Al_XGa_1-XIt is a curve when x of As is 1, 0.5, 0, the vertical axis is the ratio d / Λ of the diameter d of the hole 11 and the distance 間 between the hole centers, and the horizontal axis is the distance between the hole centers. The ratio of 発 振 to the oscillation wavelength λ is Λ / λ (the vertical and horizontal axes are the same in FIG. 7 described later).
[0133]
Therefore, unless the holes 11 are formed in the second region, the oscillation wavelength λ and the average hole center distance な る have a large diameter and the transverse mode of the laser beam cannot be unified._aveRatio with_aveIn order to satisfy both the conditions of confining the laser beam in the first region and unifying the transverse mode of the laser beam in the entire region where / λ is larger than 2, the circle of the hole 11 of the innermost hole row must be satisfied. Average diameter d of_aveAnd the average hole center distance between the holes の_aveRatio d_ave/ Λ_aveMust be greater than 0.016 and less than 0.2.
[0134]
Note that the curve groups B and C in FIG. 6 are based on the refractive index (having a value between 3.0 and 3.6 depending on the composition) of AlGaAs which is a material system used in the VCSEL having an oscillation wavelength of 850 nm as described above. The same applies to the InGaAsP system (refractive index: 3.0 to 3.4) which is a material system used in a VCSEL having an oscillation wavelength of 1550 nm.
[0135]
However, a GaN-based material (refractive index: 2.0 to 2.4) or the like, which is a material used in a VCSEL having an oscillation wavelength of 400 nm, has a considerably small refractive index. Become like
[0136]
That is, the two upper curves shown in FIG. 7 (curve D represents GaN and curve E represents AlN) are lines that give the normalized frequency v = 2.405 for the GaN system, and are lower than this line. The predetermined oscillation wavelength λ, the average diameter d of the holes 11 in the innermost hole row_aveAnd average hole center distance 空_aveWith the dimensions described above, the transverse mode can be unified.
[0137]
The lower two curves in FIG. 7 (curve F indicates GaN and curve G indicates AlN) are lines that give the normalized frequency v = 0.6 for the GaN system, and are above this line. The predetermined oscillation wavelength λ, the average diameter d of the holes 11 in the innermost hole row_aveAnd average hole center distance 空_aveWith this dimension, the laser light can be more confined in the first region.
[0138]
Therefore, in a GaN-based material (refractive index: 2.0 to 2.4) or the like, which is a material system used in a VCSEL having an oscillation wavelength of 400 nm, unless the holes 11 are formed in the second region, the transverse mode of the laser beam is unified. Wavelength λ and average hole center distance な る_aveRatio with_aveIn order to satisfy both the conditions of confining the laser beam in the first region and unifying the transverse mode of the laser beam in the entire region where / λ is larger than 2, as shown in FIG. Average diameter d of the circle of the holes 11 in the row_aveAnd the average hole center distance between the holes の_aveRatio d_ave/ Λ_aveMust be larger than 0.03 and smaller than 0.23.
[0139]
Next, a method of manufacturing the VCSEL 101 configured as described above will be described.
[0140]
The method of manufacturing the VCSEL 101 according to the second embodiment differs from the method of manufacturing the VCSEL 1 of the first embodiment only in the step of ST102, and the other steps are the same as those of the first embodiment. Therefore, only the step of ST102 will be described, and the other steps will be omitted. In the following description, the same components as those described in the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted.
[0141]
That is, after the crystal is grown up to the cap layer 6 in ST101, patterning is performed with, for example, a photoresist as shown in FIGS. 10 and 18, and the space of the innermost peripheral hole row is formed from the cap layer 6 to the upper part of the lower DBR mirror 3a. The hole 11 has an average diameter d_aveIs 0.9 μm, the average distance between hole centers 中心_aveIs 9 μm, and the size and arrangement of the holes 11 in the holes 11 other than the innermost hole row may vary, but the standardized frequency v obtained from the effective refractive index of the second region as a whole, etc. Are formed by reactive ion etching (RIE) using a Cl-based gas so that is larger than 0.6 and smaller than 2.405 (ST102). At this time, the depth M of the hole 11 is set to about 4 μm.
[0142]
The subsequent manufacturing method of the VCSEL 101 is the same as that of the first embodiment as described above, and therefore will not be described. However, in order to finally produce a VCSEL, for example, a step of cleaving a chip for each element or a stem (mount with foot) is used. A die bonding step, a step of wire bonding the electrode and the stem on the surface, and a step of caps and seals for shutting off the outside air are required.
[0143]
As described above, according to the present embodiment, the first region is surrounded along the resonance direction of light, and the difference between the refractive index of the first region and the effective refractive index becomes small. In addition to the formation of the second region and the formation of an electrode for injecting current into the first region and an insulator for preventing current from entering the second region, the light of the higher-order transverse mode can be transmitted to the first region. The single mode laser light is confined and guided in the first region without being guided through the region, and the transverse mode emitted as the laser light is unified despite its high output due to the large aperture, and its The threshold current can be reduced.
[0144]
Specifically, from the cap layer 6 and the upper DBR mirror 3b to the upper part of the lower DBR mirror 3a, a plurality of holes 11 filled with air penetrating the first region along the light resonance direction are formed. Then, the second region of the cap layer 6 is covered with the insulating layer 7 and the upper electrode 8 contacts the cap layer 6 only in the ring-shaped region on the first region. It is possible to easily obtain a desired effective refractive index slightly smaller than the refractive index of the first region by adjusting the size, quantity, etc. of the laser beam. Nevertheless, the threshold current of the VCSEL 101 can be reduced by unification and efficient current injection.
[0145]
Further, since the upper electrode 8 is in contact with the cap layer 6 only in a ring-shaped region having an outer diameter of about 14 μm and an inner diameter of about 10 μm, the resistance is not increased and the holes 11 are formed. The second mode does not become too far from the oscillation area, and the transverse mode emitted as laser light by the action of the hole 11 can be unified irrespective of the high output due to the large aperture.
[0146]
Furthermore, since the air is filled in the holes 11, the manufacturing cost can be reduced as compared with a case where another material is newly filled.
[0147]
Further, since the formed holes 11 are immediately closed with a photoresist or the like, it is possible to prevent impurities such as dust from adhering to the inner walls of the holes 11 and prevent the VCSEL 101 from deteriorating.
[0148]
Further, a cross section orthogonal to the refractive index of the first region, the effective refractive index of the second region, the oscillation frequency of the laser light oscillated by the first region, and the resonance direction of the first region is a circular cross section. Since the normalized frequency v obtained as a parameter with the radius at the time is set to be larger than 0.6 and smaller than 2.405, the laser light is emitted to the first region which is the oscillation region while reducing the threshold current. Is confined, and the transverse mode of the emitted laser light can be unified.
[0149]
In addition, the average hole center distance between each hole in the innermost hole line array Λ_aveAnd the oscillation wavelength λ_ave/ Λ is larger than 2, so that the diameter of the first region viewed from the resonance direction of the light such that the transverse mode of the emitted laser light cannot be unified in, for example, a conventional oxidation-confined VCSEL. Is 4 times or more of λ, the transverse mode of the emitted laser beam can be further unified while reducing the threshold current.
[0150]
Furthermore, the average diameter d of a circle corresponding to the area of the hole 11 in the innermost hole row_aveAnd the average hole center distance between each hole 同 士_aveRatio d_ave/ Λ_aveIs larger than 0.016 and smaller than 0.2, the plurality of holes 11 in the innermost hole row are formed. Therefore, while the threshold current is reduced, for example, the oscillation region of the VCSEL 101 of AlGaAs or InGaAsP system is reduced. In addition to confining the laser light in the first region, the transverse mode of the emitted laser light can be unified.
[0151]
For example, in the GaN-based VCSEL 101, d_ave/ Λ_aveIs larger than 0.03 and smaller than 0.23, so that the plurality of holes 11 in the innermost hole row are formed. In addition to confining the laser light in the first region, the transverse mode of the emitted laser light can be unified.
[0152]
Furthermore, in the step of covering the opening of the hole 11, the opening is covered by using polyimide or photoresist for the sealing member, so that the opening can be easily covered, and the manufacturing cost can be reduced.
[0153]
In addition, among the holes 11 formed in the second region, the holes 11 other than the holes 11 in the innermost hole row are standardized by the effective refractive index of the second region as a whole. If the formation frequency v is larger than 0.6 and smaller than 2.405, the size and arrangement of the holes 11 may be different, so that the manufacturing cost can be reduced.
[0154]
Further, the holes 11 themselves of the innermost hole row also have an average diameter d._aveAnd average hole center distance 空_aveSatisfies certain conditions, the diameter d of each of the holes 11 and the distance Λ between the centers of the holes do not need to be the same, so that a strict system is not required and the manufacturing cost can be reduced.
[0155]
Next, a magneto-optical recording / reproducing apparatus will be described as an example of an electronic apparatus including a VCSEL according to a third embodiment of the present invention. The VCSEL provided in this magneto-optical recording / reproducing apparatus will be described as VCSEL1, but is not limited to VCSEL1, and may be VCSEL101. The same components as those of the VCSEL 1 according to the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
[0156]
FIG. 19 is a schematic configuration diagram of a magneto-optical recording / reproducing apparatus which is an example of an electronic apparatus according to the third embodiment of the present invention.
[0157]
As shown in FIG. 19, a magneto-optical recording / reproducing device 201 reads and writes information from and to a spindle motor 202 that rotates an optical disk such as a CD-R (CD-Recordable) or a CD-RW (CD-ReWritable). It comprises a pick-up unit 203, an interface unit 204 for taking in external information or outputting information to the outside, and a control unit 205 for controlling these.
[0158]
Here, as shown in FIG. 19, the pickup unit 203 is a VCSEL 1 that emits a high-output laser beam having a reduced threshold current and a single transverse mode, and uses the laser beam emitted from the VCSEL 1 as a tracking servo. A grating 206 that generates three necessary spots, a polarized beam splitter (PBS) 207 that transmits approximately 100% of the outward laser beam, and a collimator lens (CL) that converts the laser beam transmitted through the polarized BS 207 into parallel light. lens) 208, a λ / 4 plate 209 that converts the laser light converted into parallel light by the collimator lens 208 into circularly polarized light, and the laser light converted into circularly polarized light by the λ / 4 plate 209 onto an optical disc 210 such as a CD-RW. Focused objective lens 211, polarized on the return path The laser beam reflected by the BS 207 is composed of a cylindrical lens 212 for generating astigmatism required for focus servo, a pattern division PD (PD: Photo Diode) 213 for receiving pit signals and the like.
[0159]
Next, the operation of the magneto-optical recording / reproducing apparatus 201, which is an example of the electronic apparatus including the VCSEL 1 configured as described above, will be briefly described focusing on the optical operation.
[0160]
First, when the power of the magneto-optical recording / reproducing apparatus 201 is turned on, the spindle motor 202 rotates at a predetermined rotation speed in accordance with an instruction from the control unit 205, and simultaneously drives a sled motor (not shown) to move the position of the predetermined optical disk 210 to a predetermined position. Then, the pickup unit 203 is moved.
[0161]
When a predetermined current is injected into the upper electrode 8 under the control of the control unit 205, the current is regulated by the insulating layer 7, and the current flows from the contact area with the ring-shaped cap layer 6 on the first area. Only enters the cap layer 6 and the like. As a result, the current can be efficiently injected into the oscillation region, and the threshold current of the VCSEL 1 can be reduced.
[0162]
Further, light is generated in the active layer 5 by the efficiently injected current, and a hole 11 is formed in an in-plane direction (horizontal direction, XZ plane direction in FIGS. 1 and 2) orthogonal to the light resonance direction. Since the effective refractive index of the second region is slightly smaller in the first region, which is a non-exposed region, and in the second region in which the holes 11 are formed outside the first region, the so-called cladding layer is used. Functioning, the light generated in the first region has a small difference in refractive index even though the width of the waveguide is wide, so that the light in the single transverse mode is near the boundary between the first region and the second region. The light is guided as a whole in the light resonance direction (Y direction in FIGS. 1 and 2), is reflected by the semiconductor multilayer DBR mirror 3 sandwiching the active layer 5 and the like up and down, and resonates. The light is amplified and oscillated as a laser beam, and is emitted from the emission port 10.
[0163]
Further, the laser light emitted from the VCSEL 1 passes through the grating 206, passes through the polarized light BS 207, is made parallel by the collimator lens 208, becomes circularly polarized light by the λ / 4 plate 209, and becomes an optical disk 210, for example, a CD-RW by the objective lens 211. The required information is written at a predetermined position such as the focus of the high-power laser light.
[0164]
In the case of reproduction, the laser beam reflected by the optical disk 210 enters the return path and follows the reverse course to the polarized light BS 207, is reflected by the polarized light BS 207 in the direction of the cylindrical lens 212, enters the cylindrical lens 212, and enters the astigmatism. An aberration is generated, and the light enters the pattern division PD 213.
[0165]
Further, the pattern division PD 213 on which the laser light is incident receives a pit signal, a tracking signal, a focus signal, and the like, and outputs the signal information to the control unit 205.
[0166]
The control unit 205 outputs the input signal information to the interface unit 204 and outputs the information to an external electronic device such as a display device, or when the magneto-optical recording / reproducing device 201 has an output unit such as a display device. With these, signal information is converted into display information and the like.
[0167]
As described above, according to the present embodiment, holes are formed in the second region surrounding the first region serving as the optical waveguide, and the difference in refractive index between the first region and the first region is reduced. Since the VCSEL 1 is provided with an electrode for injecting a current into the first region and an insulator for preventing the current from entering the second region, the threshold current of the VCSEL 1 is increased even if the output port is enlarged to 10 μm or more and the output is increased. The transverse mode can be made a single mode while reducing the power, and writing (both magneto-optical recording and phase change) at a high rotation speed and high transfer speed becomes possible.
[0168]
Specifically, for example, the centers of the nearest holes are regularly arranged in a triangular lattice shape so as to form an equilateral triangle, and the diameter d of a circle corresponding to the area of the holes and the space between the holes are determined. The plurality of holes 11 are formed so that the ratio d / Λ to the distance between the hole centers is larger than 0.016 and smaller than 0.2, and the second region of the cap layer 6 is covered with the insulating layer 7. Since the VCSEL 1 such as an AlGaAs-based or InGaAsP-based device is provided in which the upper electrode 8 is in contact with the cap layer 6 only in the ring-shaped region (electrode contact region), the emission port is expanded to 10 μm or more, and the threshold current is reduced even when the output is high The transverse mode of the emitted laser beam can be made a single mode, and writing (both magneto-optical recording and phase change) at a high rotation speed and a high transfer speed becomes possible.
[0169]
Further, for example, the GaN-based VCSEL 1 includes the VCSEL 1 in which a plurality of holes are formed so that d / Λ is larger than 0.03 and smaller than 0.23. As the output, the transverse mode of the laser light emitted while reducing the threshold current can be made a single mode, and writing (both magneto-optical recording and phase change) at high rotation speed and high transfer speed becomes possible. .
[0170]
In addition, portable electronic devices are particularly required to have lighter and smaller components. If the VCSEL 1 is provided, the semiconductor laser emits a laser beam with a high output and a single transverse mode while reducing the threshold current. A small and light-weight chip structure can be achieved, and the weight and size of parts can be further reduced.
[0171]
Note that the present invention is not limited to any of the above-described embodiments, and can be appropriately modified and implemented within the scope of the technical idea of the present invention.
[0172]
For example, in the above-described embodiment, the magneto-optical recording / reproducing apparatus 201 has been described as an example of the electronic apparatus including the VCSEL 1. However, the present invention is not limited to this. Voids are formed in the second region to reduce the difference in refractive index from the first region, and prevent current from intruding into the second region and the electrode for injecting current into the first region. Since the VCSEL 1 provided with an insulator is provided, even if the emission port is enlarged to 10 μm or more and a high output is obtained, the transverse mode of the emitted laser light can be reduced to a single mode while reducing the threshold current. Since the diameter of the light spot can be reduced, precise processing becomes possible.
[0173]
In a printing device such as a laser beam printer, a hole is formed in a second region surrounding the first region serving as a light waveguide, so that a difference in refractive index from the first region is reduced. In addition, by providing the VCSEL 1 having an electrode for injecting current into the first region and an insulator for preventing current from entering the second region, the light intensity distribution of the laser beam is reduced while the threshold current is reduced. Can be made into a single-peak shape, so that the uniformly charged photosensitive drum is locally irradiated with a laser to remove electricity, thereby forming an area where toner does not adhere and creating a plate. It can be formed without falling off.
[0174]
Furthermore, by arranging a plurality of VCSELs 1 having a high light emission intensity of 10 mW or more while reducing the threshold current, it is possible to simultaneously remove electricity from a plurality of portions of the photosensitive drum and to shorten the irradiation time due to the high light emission intensity. It becomes.
[0175]
In other words, the VCSEL 1 capable of emitting a single transverse mode laser beam with a large output while reducing the threshold current can provide a laser beam printer capable of high-definition and high-speed printing.
[0176]
Further, in the above-described embodiment, a case has been described in which the holes 11 formed in the second region are filled with, for example, air. However, the present invention is not limited to this, and the refractive index is lower than the medium in the first region. The material may be filled. Thereby, the effective refractive index of the second region can be further finely adjusted, and a desired effective refractive index slightly smaller than the refractive index of the first region can be more easily obtained.
[0177]
Furthermore, in the above-described embodiment, the contact region (electrode contact region) between the upper electrode 8 and the cap layer 6 is formed in a ring shape, for example. However, the present invention is not limited to this. The refractive index of the first region and the second region Any difference between the contact region and the effective refractive index of the region can be made small, the transverse mode can be unified even if the emitted laser beam has a large output, and the threshold current can be reduced. Shape may be sufficient.
[0178]
In the above-described embodiment, the contact region (electrode contact region) between the lower electrode 9 and the substrate 2 is formed, for example, on the entire surface of the substrate. However, the present invention is not limited to this, and the contact region between the upper electrode 8 and the cap layer 6 ( The electrode contact region may be formed in a ring shape, for example, and the contact region between the lower electrode 9 and the substrate 2 may be formed in a ring shape or the like. As a result, the current can be more efficiently injected into the oscillation region, and the threshold current can be further reduced.
[0179]
Furthermore, in the above-described embodiment, for example, the holes 11 are formed to penetrate from the cap layer 6 to the upper portion of the lower DBR mirror 3a. However, the present invention is not limited to this. It can also be limited to the vicinity of the interface with the cladding layer 4b. As a result, it is possible to avoid a decrease in luminous efficiency due to a non-radiative recombination current of carriers generated at a vacancy interface or the like of the active layer 5.
[0180]
【The invention's effect】
As described above, in the present invention, the threshold current can be reduced while the transverse mode is stable and a single mode with a high output due to a large aperture.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a VCSEL according to a first embodiment of the present invention.
FIG. 2 is a sectional view taken along the line AA ′ of FIG.
FIG. 3 is a diagram for explaining an arrangement of holes in the VCSEL according to the first embodiment of the present invention, for example, an explanatory diagram in which an active layer is viewed from above.
FIG. 4 is a schematic perspective view of a mesa structure of the VCSEL.
FIG. 5 is an explanatory diagram of an electrode contact region viewed from above with polyimide or photoresist of FIG. 4 removed;
FIG. 6 is a graph illustrating a boundary condition between a single mode and a higher mode.
FIG. 7 is a graph illustrating a boundary condition between a GaN-based single mode and a higher mode.
FIG. 8 is a flowchart of a VCSEL manufacturing method according to the first embodiment of the present invention.
FIG. 9 is an explanatory diagram of a crystal growth step in the manufacturing process of the VCSEL according to the first embodiment of the present invention.
FIG. 10 is an explanatory diagram of a hole forming step which is the next step of FIG. 9;
FIG. 11 is an explanatory view of a hole confinement step which is the next step of FIG. 10;
12 is an explanatory diagram of a step of forming a mesa, which is the next step of FIG.
13 is an explanatory diagram of a step of forming an insulating layer, which is the next step of FIG. 12. FIG.
14 is an explanatory diagram of a step of forming the upper electrode, which is the next step of FIG.
15 is an explanatory diagram when the upper electrode of FIG. 14 is viewed from above.
FIG. 16 is an explanatory view of a step of forming an emission port, which is the next step of FIG. 14;
FIG. 17 is an explanatory diagram of a lower electrode forming step which is the next step of FIG. 16;
FIG. 18 is a diagram for explaining the arrangement of holes in the VCSEL according to the second embodiment of the present invention, for example, an explanatory diagram in which an active layer is viewed from above.
FIG. 19 is a schematic configuration diagram of a magneto-optical recording / reproducing apparatus which is an example of an electronic apparatus according to a third embodiment of the present invention.
[Explanation of symbols]
1,101 VCSEL
2 substrate
3 DBR mirror
3a Lower DBR mirror
3b Upper DBR mirror
4 Cladding layer
4a Lower cladding layer
4b Upper cladding layer
5 Active layer
6 Cap layer
7 Insulation layer
8 Upper electrode
9 Lower electrode
10 Outlet
11 holes
12 Mesa
13a, 13b Polyimide or photoresist
201 Magneto-optical recording / reproducing device
202 spindle motor
203 Pickup unit
204 interface
205 control unit
206 grating
207 Polarized BS
208 Collimator lens
209 λ / 4 plate
210 Optical Disk
211 Objective lens
212 cylindrical lens
213 Pattern division PD

Claims (18)

A first region having a first refractive index and the first region surrounding the first region along the direction of light resonance, wherein the effective refractive index is different from the first refractive index, and the difference is slight; An active layer having a second region having a suitable second refractive index;
An electrode for injecting a current into the first region;
A surface-emitting laser, comprising: an insulator for preventing current from entering the second region. The surface emitting laser according to claim 1,
The surface emitting laser according to claim 1, wherein the insulator is formed between the second region and the electrode. The surface emitting laser according to claim 2,
The surface emitting laser according to claim 1, wherein the electrode is formed in a ring shape surrounding an emission port of the laser light oscillated by the first region so as to be in contact with the first region. The surface emitting laser according to claim 3,
The surface emitting laser according to claim 1, wherein the insulator is formed using polyimide or photoresist. The surface emitting laser according to claim 4,
The surface emitting laser according to claim 1, wherein the second region has a plurality of holes formed in the member of the first region. The surface emitting laser according to claim 5,
The surface emitting laser according to claim 1, wherein the holes are formed through the active layer in the resonance direction. The surface emitting laser according to claim 6,
The surface emitting laser according to claim 1, wherein the holes are sealed. The surface emitting laser according to claim 7,
The hole has a circular cross section perpendicular to the first refractive index, the second refractive index, the oscillation frequency of the laser light oscillated by the first region, and the resonance direction of the first region. A surface-emitting laser characterized in that a normalized frequency obtained by using a radius at that time as a parameter is larger than 0.6 and smaller than 2.405. The surface emitting laser according to claim 8,
The plurality of holes that surround the first region and that are closest to the first region have a ratio Λ _ave / λ between the average value Λ _{ave of the} distance between the centers of the holes and the oscillation wavelength λ that is larger than 2. A surface emitting laser. The surface emitting laser according to claim 9,
The plurality of holes that surround the hole closest to the first region are the average value d _ave of the diameter of a circle corresponding to the area of each of the plurality of holes and the distance between the hole centers. greater than the ratio _{d ave} / lambda _ave and the average value lambda _ave is 0.016 and the surface emitting laser and is smaller than 0.2. The surface emitting laser according to claim 9,
The plurality of holes surrounding the first region are closest to the first region, and the average value d _ave of the diameter of a circle corresponding to the area of each of the plurality of holes and the distance between the center of the holes. greater than the ratio _{d ave} / lambda _ave and the average value lambda _ave is 0.03 and the surface emitting laser and is smaller than 0.23. The surface emitting laser according to claim 8,
The holes are arranged in the form of a triangular lattice such that the centers of the nearest holes form an equilateral triangle. A surface emitting laser characterized by being large. The surface emitting laser according to claim 12,
The hole is characterized in that a ratio d / Λ between a diameter d of a circle corresponding to the area of the hole and the distance Λ between the centers of the holes is larger than 0.016 and smaller than 0.2. Light emitting laser. The surface emitting laser according to claim 12,
The hole is characterized in that a ratio d / Λ between a diameter d of a circle corresponding to the area of the hole and the distance 中心 between the centers of the holes is larger than 0.03 and smaller than 0.23. Light emitting laser. A first region having a first refractive index and the first region surrounding the first region along the direction of light resonance, wherein the effective refractive index is different from the first refractive index, and the difference is slight; An active layer having a second region having a suitable second refractive index;
An electrode for injecting a current into the first region;
An electronic device, comprising: a surface-emitting laser including: an insulator that prevents current from entering the second region. A first region having a first refractive index and the first region surrounding the first region along the direction of light resonance, wherein the effective refractive index is different from the first refractive index, and the difference is slightly Forming an active layer having a second region having holes pierced in the resonance direction so as to have a suitable second refractive index;
Immediately after the step of forming the active layer is completed, a step of forming an insulator that covers an opening of the hole and prevents current from entering the second region;
Forming an electrode for injecting a current into the first region. The method for manufacturing a surface emitting laser according to claim 16,
A method of manufacturing a surface emitting laser, wherein the step of forming the insulator includes forming the insulator by using polyimide or photoresist as the insulator. The method for manufacturing a surface emitting laser according to claim 17,
In the step of forming the electrode, the electrode is formed in a ring shape surrounding an emission port of the laser light oscillated by the first region so as to be in contact with the first region. Manufacturing method of surface emitting laser.

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