JP2007273849A - Vertical cavity surface-emitting laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vertical cavity surface-emitting laser which has a confinement structure of a mechanically-stable strength to confine a current. <P>SOLUTION: The vertical cavity surface-emitting laser comprises a medium layer containing a pair of reflecting mirrors 102, 107 and an active later 104 between these reflecting mirrors on a substrate. A confinement structure 105 which confines a current composed of empty holes is produced in a medium layer 106 adjacent to either mirror of the reflecting mirrors. At that time, the medium layer including the active layer can be composed of GaN, AlN, InN or a mixed crystal of GaN, AlN and InN. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vertical cavity surface emitting laser (VCSEL).

The vertical cavity surface emitting laser has various advantages such as low threshold, low power consumption, circular spot shape, easy coupling with optical elements, and arrayable, and has been actively researched since the late 1980s. It is coming.
This vertical cavity surface emitting laser is generally provided with a current confinement structure for concentrating the injected current in a narrow range of the gain medium and lowering the threshold value.
In many cases, this constriction structure also serves as a so-called optical waveguide, in which resonance light is confined inside the constriction structure simultaneously with current.
Therefore, the threshold is lowered by the light confinement effect, and the mode control of the oscillation light can be performed.

In such a constriction structure of a vertical cavity surface emitting laser, a technique for providing a constriction layer of an insulating oxide layer such as Al ₂ O ₃ in an element in a GaAs / AlGaAs-based material has been conventionally known. Yes.
However, the constriction layer is formed by sandwiching a layer having a higher Al composition than other materials constituting the element, such as an AlAs layer, in advance during crystal growth, and selectively oxidizing them.
Therefore, distortion or due to lattice mismatch another AlGaN layer and the Al ₂ O _3, such as by volume shrinkage due to become Al ₂ O _3, defects may occur in the element, the element in the process after oxidation It had the subject that reliability fell, such as breaking.

For this reason, for example, Patent Document 1 proposes a surface emitting laser having a constricted structure using an air gap.
In this method, a normal vertical cavity surface emitting laser processed into a mesa is subjected to selective side etching of an AlAs layer to form a narrowed structure of an air gap.
JP 2005-93704 A

  However, since the air gap constriction structure by side etching of the element supports the element only in the region of the center number μmΦ of the constriction structure, it is not always satisfactory in terms of the mechanical strength of the constriction part. Improvement is desired.

  In view of the above problems, an object of the present invention is to provide a vertical cavity surface emitting laser having a constricted structure for confining current with stable mechanical strength.

In order to solve the above problems, the present invention provides a vertical cavity surface emitting laser configured as follows.
The vertical cavity surface emitting laser of the present invention is a vertical cavity surface emitting laser having a pair of reflecting mirrors and a medium layer including an active layer provided between the reflecting mirrors on a substrate.
The medium layer adjacent to one of the pair of reflecting mirrors has a constriction structure for confining a current formed by holes.
In the vertical cavity surface emitting laser according to the present invention, the medium layer including the active layer is composed of GaN, AlN, InN, or a mixed crystal thereof. In the vertical cavity surface emitting laser of the present invention, the medium layer including the active layer is composed of GaAs, AlAs, GaP, InP, or a mixed crystal thereof.
The vertical cavity surface emitting laser according to the present invention is characterized in that at least one of the pair of reflecting mirrors has a periodic structure having a refractive index with respect to a direction perpendicular to a light resonance direction. To do.
The vertical cavity surface emitting laser of the present invention is characterized in that the holes have a thin ring shape in a plane parallel to the substrate.
The vertical cavity surface emitting laser of the present invention is characterized in that the holes have a shape in which the thin ring shape has anisotropy.
Also, the vertical cavity surface emitting laser of the present invention is characterized in that the holes have a three-dimensional shape spreading in the resonance direction of light.
The vertical cavity surface emitting laser of the present invention is characterized in that the holes are holes formed by internal processing with an ultrashort pulse laser in a medium layer including an active layer.

  According to the present invention, it is possible to realize a vertical cavity surface emitting laser having a constricted structure for confining current with stable mechanical strength.

  According to the embodiment of the present invention, in the surface emitting laser element, the current confinement and the optical confinement structure are constituted by the air gap, and the air gap structure is formed in the medium layer adjacent to one of the pair of reflection mirrors. The structure formed by (hollow structure) can be taken.

Next, a vertical cavity surface emitting laser according to an embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view for explaining the basic configuration.
In FIG. 1, 101 is a substrate, 102 and 107 are lower and upper resonator mirrors, 103 and 106 are lower and upper cladding layers, 104 is an active layer, and 105 is an air gap current confinement structure.
The basic structure of the vertical cavity surface emitting laser in the present embodiment is the same as that of a normal vertical cavity surface emitting laser.
First, a resonator constituted by a pair of resonator mirrors and a gain region therein is provided on a substrate, and an electrode (not shown) for current injection is provided.
A current confinement structure for confining the injected current in a narrow range of the gain region is provided at any position in the resonator including the mirror portion.
At this time, in this embodiment, a constriction structure for confining current and light formed by holes is formed in the medium layer adjacent to one of the pair of reflection mirrors.

Next, the air gap type constriction structure of the present embodiment will be described.
The air gap type confinement structure of this embodiment performs current confinement by concentrating current in a narrow range of the gain region, and at the same time, forms a waveguide structure based on a refractive index difference in the resonator to confine the resonance light. Also plays a role.
The preferred embodiment of the air gap structure will be further described.
Since the air gap structure has a lower refractive index than that of the oxidized constriction structure, if the volume is large, oscillation tends to become multimode. Therefore, it is preferable that the volume is not too large.
Further, since the effect of optical confinement can be reduced by separating the constriction structure from the active layer, it is preferable that the confinement structure is separated from the active layer to some extent.
However, since the current confinement effect is lost as the constriction structure is further away from the active layer, it is necessary to consider the separation distance in consideration of the current confinement effect determined by the current diffusion length.

A material having a smaller current diffusion length is preferable because the effect of current confinement is not impaired even if the constriction structure is separated from the active layer.
An example of a material having a short current diffusion length is semiconductor GaN (<1 μm / μm, p-type). The numerical value means (diffusion length) / (current flow distance).
As a guideline for the design of the constriction structure, a method of reducing the thickness of the constriction structure (light resonance direction) as much as possible and then disposing the constriction structure away from the active layer so as not to impair the current confinement effect. Take.
In addition, functions other than current and light constriction can be added by controlling the shape of the air gap.
For example, the current injection efficiency is improved by making the shape of the gap anisotropic in a plane parallel to the substrate, or by controlling the polarization, or by using a three-dimensional shape instead of a layered shape. It is possible to adopt such a method. These details will be described in later examples.

As an active layer constituting the resonator in the surface emitting laser according to the embodiment of the present invention, a double hetero structure, a multiple quantum well structure, a quantum dot structure, which are used in a normal vertical cavity surface emitting laser, Etc. can be applied directly.
Further, a solid gain medium such as Ti: Sapphire or YAG (Yittrium Aluminum Garnet) can be used as it is.
Further, L = active layer thickness + cladding layer thickness resonator length + mirror phase shift × λ / 2π (effective resonator length, λ is the wavelength of resonance light) is NL = (n / 2) λ. To design. N is the average refractive index of the resonator, and n is an arbitrary positive integer.
Moreover, it is preferable to design so that the position of the active layer comes to the position of the antinode of the standing wave in each resonator.

Moreover, the mirror which comprises the resonator in the surface emitting laser of embodiment of this invention can be applied from several types.
For example, a DBR (Distributed Bragg Reflection) mirror often used for a normal vertical cavity surface emitting laser, or a mirror provided with a periodic structure of refractive index in a direction perpendicular to the resonant light in the resonator, etc. Can be applied.
The latter refractive index periodic structure may be one-dimensional or two-dimensional. It is known to function as a mirror by making light incident on such a refractive index periodic structure from a direction perpendicular to the surface.
In the embodiment of the present invention, any one of the above-described mirrors, such as two, or one of them can be employed.

Next, materials constituting the vertical cavity surface emitting laser according to the embodiment of the present invention will be described.
First, regarding the material inside the resonator (cladding layer + active layer), various types of semiconductors and dielectrics can be used.
In the semiconductor, for example, the following materials can be applied.
III-V group semiconductors such as GaAs, AlGaAs, AlGaInP, GaInAsP, GaInNAs, GaN, AlN, and InN. Furthermore, mixed crystals containing any ratio of elements constituting these materials can be applied. Furthermore, II-VI group semiconductors such as ZnSe, CdS, and ZnO and mixed crystals of any proportion of the elements constituting them can also be applied.
As the dielectric, a solid laser medium such as Ti: Sapphire or YAG (Yittrium Aluminum Garnet) can be used.
The above medium can be arbitrarily combined with the cladding and the active layer.
However, in order to operate by current injection, the medium constituting the resonator internal structure is preferably a semiconductor.
In the case of a semiconductor, the cladding layer usually uses a p-type semiconductor on the positive electrode side, an n-type semiconductor on the negative electrode side, and a non-doped semiconductor on the active layer.

The material constituting the mirror is the above-mentioned semiconductor, metal such as Au, Ag, Cr, or dielectric such as SiO ₂ , TiO ₂ , HfO ₂ , Al ₂ O ₃ , Nb ₂ O ₅ , or CeO _2. It is possible to use. Alternatively, any materials such as conductive oxides such as ITO (Indium Tin Oxide), SnO ₂ , and In ₂ O ₃ can be used in any combination.
However, when oscillating by current injection through a mirror, it is preferably a semiconductor, metal or conductive oxide.
In addition to laser materials other than those listed above, any of metals, semiconductors, dielectrics, and conductive oxides can be used. A semiconductor, metal, or conductive oxide is preferable.

As a means for injecting carriers into the active layer 104, for example, a method of having a pair of electrodes of an anode and a cathode and injecting carriers into the active layer by injecting current from the electrodes can be employed.
As the electrode, a ring electrode used in a normal VCSEL can be used, and electrodes having various shapes such as a circle and a rectangle can be used.
About the material of an electrode, it depends on the laser element material of the site | part which forms an electrode.
For example, materials such as Au—Ge—Ni and Au—Sn can be used for n-type GaAs, and Au—Zn and In—Zn can be used for p-type GaAs.
A transparent electrode such as ITO can also be used. In particular, when an electrode other than the ring electrode is formed on the light emitting surface of the element, it is desirable to use an electrode that is transparent to the oscillation wavelength.

The vertical cavity surface emitting laser according to the embodiment of the present invention can be manufactured using the following manufacturing process.
That is, most of the vertical cavity surface emitting lasers according to the embodiments of the present invention can be manufactured using a known vertical cavity surface emitting laser manufacturing process.
Among them, regarding the narrowed structure of the air gap, a manufacturing method different from that of a normal vertical cavity surface emitting laser is used to form a hollow structure inside the element.
As such a technique, for example, internal processing of a transparent body by an ultrashort pulse laser such as a femtosecond laser can be used.
According to this technique, a hollow structure can be produced with good controllability in a medium that is transparent to laser light, so that a narrow structure of an air gap can be produced without using a side etching technique.
In the present embodiment, the air gap current confinement structure 105 is formed in the upper clad layer 106 using such a technique.

Examples of the present invention will be described below.
[Example 1]
In Example 1, a vertical cavity surface emitting laser configured by applying the present invention will be described.
FIG. 2 shows a schematic cross-sectional view in the direction perpendicular to the substrate through the central portion of the vertical cavity surface emitting laser in the present embodiment.
In FIG. 2, 201 is a substrate, 202 is a lower resonator mirror, 203 is a lower resonator cladding layer, 204 is an active layer, 205 is a constricted structure, 206 is an upper resonator cladding layer, 207 is an upper resonator mirror, and 208 is An n-side electrode 209 is a p-side electrode. The substrate 201 is a GaAs substrate, and the resonator is configured as follows. The lower and upper resonator mirrors 202 and 207 have n-type and p-type Al _0.5 Ga _0.5 As / Al _0.93 Ga _0.07 As DBR mirrors, and the active layer 204 has an AlInGaP / GaInP multiple quantum well structure.
Also, the constriction structure 205 is a buried air gap constriction structure layer, and the lower and upper clad layers of 203 and 206 are n-type and p-type (Al _0.5 In _0.5 ) _0.5 Ga _0.5 P, respectively.
The n-side and p-side electrodes 208 and 209 are Au—Ge—Ni and Au—Zn, respectively.

The surface emitting laser in this example is a semiconductor laser that emits red light of 670 nm. Hereinafter, each part will be described in detail.
The DBR mirrors are the upper and lower resonator mirrors, and Al _0.5 Ga _0.5 As (low refractive index layer) / Al _0.93 Ga _0.07 As (high refractive index layer) are 38 pairs and 70 pairs, respectively. It consists of one by one.
The thickness of each layer is λ / 4 of the oscillation wavelength in terms of the optical path length. In this embodiment, they are 48 nm and 50 nm, respectively.
The quantum well structure of the active layer is composed of three quantum well layers and has a thickness of 6 nm. The thicknesses of the upper cladding layer and the lower cladding layer are each 500 nm.
The distance between DBR mirrors (= resonator length) is 1050 nm, which is a 5.5 wavelength resonator with respect to the oscillation wavelength.

Next, the constriction structure in the present embodiment will be described.
FIG. 3 is a cross-sectional view of the surface emitting laser according to the present embodiment taken along a line ab in FIG. 2 in a direction parallel to the substrate.
In FIG. 3, 301 is the central structure of the constriction, 302 is the air gap constriction layer, and 303 is the outer portion of the constriction structure.
In the air gap constriction structure of this embodiment, the current mainly flows through 301 constriction structure centers.
Further, as described above, it acts as a waveguide for the resonant light. In this embodiment, the cross-sectional area is made as small as 3 μmΦ so that the resonant light oscillates in a single mode.
The diameter of the outer periphery of the constriction structure is 18 μmΦ, and the diameter of the mesa is 20 μmΦ.
Further, the thickness of the air gap constriction structure in the direction parallel to the optical resonance in the element and the position from the active layer will be described. For the reasons described above, it is necessary to optimize the thickness of the air gap structure (light resonance direction) and the distance from the active layer at the same time.
In this embodiment, the thickness of the air gap is 40 nm, and the current diffusion length of p-type (Al _0.5 In _0.5 ) _0.5 Ga _0.5 P is as short as ˜1 μm / μm, so the distance from the active layer should be kept at 400 nm. ing.

The surface emitting laser in this example is manufactured as follows.
First, a resonator structure from the lower DBR mirror to the upper DBR mirror is manufactured collectively by normal crystal growth on a GaAs substrate. This can be the same as the manufacturing process of a normal VCSEL element.
The narrowing structure of the air gap can be manufactured by an internal processing technique of a transparent body using an ultrashort pulse laser.
In the present embodiment, a pulse laser obtained by reproducing and amplifying a femtosecond Ti: Sappire laser is used.
This is condensed by a condenser lens, and the light density at the focal point is increased to form a hollow structure in a desired region.
The sample can be moved by placing an element on the stage and controlled by a piezo actuator, and a laser beam can be scanned by moving the sample to form a hollow structure of any shape.
In this embodiment, a ring-shaped hollow structure having a very thin thickness as shown in FIG. 3 is formed. Finally, the p electrode Au—Ge—Ni is formed by vapor deposition, and the n electrode Au—Zn is formed by sputtering.

Further, when forming the hollow structure, a cylindrical hollow structure with a small diameter connected to the back surface of the substrate may be formed (not shown in FIG. 2).
This cavity structure functions as an exhaust port for unnecessary substances (so-called shavings) discharged when the cavity is formed inside the device.
This cavity can be formed by condensing laser light on the back surface of the substrate of the device, scanning in the direction of the active layer of the laser, and operating until reaching the region where the hollow structure is formed.
When the laser element in this embodiment is energized, it oscillates and emits red light.
The provided air gap constriction structure makes it possible to concentrate the injection current in a narrow range of the active layer and to obtain a laser element having excellent mechanical strength.

[Example 2]
In the second embodiment, a configuration example using a two-dimensional photonic crystal for the upper resonator mirror will be described.
FIG. 4 is a diagram illustrating a configuration example of this embodiment.
FIG. 4A is a schematic cross-sectional view in the direction perpendicular to the substrate passing through the central portion of the vertical cavity surface emitting laser in the present example.
FIG. 4B is a view of the upper resonator mirror as viewed from the direction perpendicular to the surface. In FIG. 4, 401 is a substrate, 402 is a lower resonator mirror, 403 is a lower resonator cladding layer, and 404 is an active layer.
Reference numeral 405 denotes a constriction structure, 406 denotes an upper resonator cladding layer, 407 denotes an upper resonator mirror high refractive index layer, 408 denotes an upper resonator mirror low refractive index medium, 409 denotes an n-side electrode, and 410 denotes a p-side electrode. .
In the present embodiment, since the element structure and materials other than the upper resonator mirror and the p-side electrode are all the same as those in the first embodiment, only those two will be described.

First, the upper resonator mirror will be described.
In this embodiment, a two-dimensional photo in which a cylindrical upper resonator mirror low refractive index medium 408 made of ITO (Indium Tin Oxide) is periodically introduced into an Al _0.5 Ga _0.5 As upper resonator mirror high refractive index layer 407. Nick crystals are used. The low refractive index media are arranged in a square lattice shape. The figure schematically shows a photonic crystal having a dozen cycles, but actually a photonic crystal having about 80 cycles is formed.
It is known that a two-dimensional photonic crystal behaves as a 100% mirror at a certain wavelength with respect to light incident perpendicularly to the surface. In this embodiment, this property is used. Hereinafter, this upper resonator mirror is referred to as a photonic crystal mirror.

The lattice parameters of the photonic crystal mirror are a period of 250 nm, a hole radius of 40 nm, and a thickness of 250 nm.
In this embodiment, since the upper resonator mirror is a photonic crystal mirror, the distance from the electrode to the constriction structure is about 350 nm, which is much thinner than that of the first embodiment.
Therefore, since there is a possibility that current is not sufficiently supplied to the central portion of the constriction structure, a transparent electrode made of ITO, not a ring electrode, is formed on the entire mirror surface in this embodiment.

In this embodiment, by providing the constriction structure in the vicinity of the photonic crystal mirror, the refractive index difference of the upper clad layer with respect to the photonic crystal can be made larger than that without the constriction structure.
The reflection characteristics of a photonic crystal mirror are generally more stable and have a higher reflectance as the refractive index difference between the mirror and the adjacent layer is larger. Therefore, by providing this constriction structure, the reflection characteristics of the mirror can be improved.
The reflection characteristics of the photonic crystal mirror improve as the constriction structure becomes closer to the mirror, but as described above, the effect of current confinement becomes lower as the constriction structure is further away from the active layer, that is, closer to the mirror. It is necessary to think together with the performance of.

The manufacturing method of the laser element in this example is the same as that in Example 1 except for the step of forming the photonic crystal mirror and the electrode.
First, it is formed in the same manner as in Example 1 until the upper cladding layer is formed.
A photonic crystal layer is formed thereon, and a periodic pattern of holes is formed by EB lithography and ICP dry etching using a Cl ₂ gas.
Further, an ITO transparent electrode film is sputtered from above.
At this time, ITO penetrates into the holes of the photonic crystal mirror and becomes an upper resonator mirror low refractive index medium.
Thereafter, the process of forming the current confinement structure and the n-electrode sputtering are the same as in the first embodiment.

[Example 3]
In the third embodiment, a configuration example in which the constriction structure is different from the above embodiments will be described.
FIG. 5 is a diagram illustrating a configuration example of this embodiment.
In this embodiment, the element configuration and materials other than the constriction structure are the same as those in the first embodiment, and therefore only the constriction structure will be described. Therefore, the cross-sectional configuration in the direction perpendicular to the substrate passing through the central portion of the laser element is also the same as that of the first embodiment, and is therefore omitted.
FIG. 5 shows a schematic cross-sectional view parallel to the substrate at the position of the constriction structure of the device for explaining the present embodiment.
In FIG. 5, reference numeral 501 denotes the central structure of the constriction, 502 is the air gap constriction structure, 503 is the constriction structure protrusion, and 504 is the outer portion of the constriction structure.

The air gap constriction structure in the present embodiment is such that the outside of the constriction structure of the first embodiment is further hollowed to give the shape anisotropy.
However, the outer peripheral portion of the constriction structure 502 is 16 μm which is 2 μm smaller than that of the first embodiment. The thickness of the light in the resonance direction is the same as in the first embodiment.
Further, the radius of curvature of the projecting portion of the 503 constriction structure is 5 μm, and the outermost portion of the projecting portion is formed at a position of 1 μm from the outer wall of the mesa.

By forming the air gap structure anisotropically in the in-plane direction parallel to the substrate as in this embodiment, anisotropy can be imparted to the refractive index difference sensed by the resonant light.
In such a case, only one direction of linearly polarized light becomes stable and oscillates. Therefore, the polarization of the oscillation light can be controlled by adopting the configuration as in this embodiment.
However, the anisotropy imparted to the air gap structure is preferably taken so that the difference in refractive index between two directions orthogonal to each other is the largest in a plane parallel to the substrate.
Therefore, as long as the above conditions are satisfied, there are several other possible anisotropies of the air gap structure that can be adopted in this embodiment.
For example, the air gap structure as a whole may be elliptical, or the air gap structure may have a rectangular cross section.
In addition to the air gap structure of the first embodiment, another minute hollow structure may be formed in the outer portion of the narrowed structure.
The manufacturing method of the laser element in this example is the same as that in Example 1, and the constriction structure is formed by adjusting the drawing pattern by the laser.

[Example 4]
In the fourth embodiment, a configuration example in which a different form from the above embodiments is applied to the constriction structure will be described.
In this embodiment, the element configuration and materials other than the constriction structure are the same as those in the first embodiment, and therefore only the constriction structure will be described.
FIG. 6 is a diagram illustrating a configuration example of this embodiment.
In FIG. 6, reference numeral 601 denotes a substrate, 602 denotes a lower resonator reflecting mirror, 603 denotes a lower resonator clad layer, and 604 denotes an active layer.
Reference numeral 605 denotes a constriction structure, 606 denotes an upper resonator cladding layer, 607 denotes an upper resonator reflection mirror, 608 denotes an n-side electrode, and 609 denotes a p-side electrode.
Regarding the cross-sectional view taken along the line ab in FIG. 6 in the direction parallel to the substrate, the configuration is the same as FIG. 3 except that the inner diameter of the constriction structure is different.

Also in the laser element in this example, since the device configuration and materials excluding the constriction structure are the same as those in Example 1, only the constriction structure will be described.
In this embodiment, the constriction structure is not a thin plane, but has a three-dimensional shape that extends in the resonance direction of the device as shown in the figure.
Specifically, as shown in FIG. 6, the cross-sectional area of the constriction structure gradually decreases as it approaches the p-side electrode.
Therefore, the injected current can be captured more efficiently and supplied to the active layer.
However, in this embodiment, since the volume of the constriction structure is larger than those in Embodiments 1 and 2, the effective refractive index difference with respect to the resonant light is also increased. For this reason, in order to oscillate in the single mode, it is necessary to make the central system of the constriction structure smaller.
In this example, the central diameter of the stenosis structure (the part where the diameter is the narrowest) is 1.5 μm.
The device manufacturing method of this embodiment is the same as that of Embodiment 1, and the constriction structure is formed by adjusting the drawing pattern by the laser.

  The configurations of the first to fourth embodiments are exemplary, and various conditions such as the structural material, size, and shape of the vertical cavity surface emitting laser of the present invention are limited by the above embodiments. It is not a thing.

1 is a schematic cross-sectional view for explaining a basic configuration of a vertical cavity surface emitting laser according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a configuration example of a vertical cavity surface emitting laser according to Embodiment 1 of the present invention. 1 is a schematic cross-sectional view showing a constriction structure portion of a vertical cavity surface emitting laser according to Embodiment 1 of the present invention. The figure explaining the structural example of the vertical cavity surface emitting laser which used the two-dimensional photonic crystal for the upper cavity mirror in Example 2 of this invention. (A) is typical sectional drawing of the orthogonal | vertical direction with respect to a board | substrate, (b) is the figure which looked at the upper resonator mirror from the perpendicular | vertical direction to the surface. The typical sectional view for explaining the example of composition of the constriction structure of the device in Example 3 of the present invention. Typical sectional drawing for demonstrating the structural example of the constriction structure of the device in Example 4 of this invention.

Explanation of symbols

101: Substrate 102: Lower resonator mirror 103: Lower clad layer 104: Active layer 105: Air gap current confinement structure 106: Upper clad layer 107: Upper resonator mirror 201: Substrate 202: Lower resonator mirror 203: Lower resonator Clad layer 204: Active layer 205: Constriction structure 206: Upper resonator clad layer 207: Upper resonator mirror 208: N-side electrode 209: P-side electrode 301: Center structure of constriction portion 302: Air gap constriction layer 303: Constriction structure External portion 401: Substrate 402: Lower resonator mirror 403: Lower resonator cladding layer 404: Active layer 405: Narrowing structure 406: Upper resonator cladding layer 407: Upper resonator mirror high refractive index layer 408: Upper resonator mirror low Refractive index medium 409: n-side electrode 410: p-side electrode 501: central structure of constriction 502: air Cap constriction structure 503: Constriction structure protrusion 504: Constriction structure outer part 601: Substrate 602: Lower resonator reflection mirror 603: Lower resonator cladding layer 604: Active layer 605: Constriction structure 606: Upper resonator cladding layer 607: Upper part Resonator reflection mirror 608: n-side electrode 609: p-side electrode

Claims (8)

In a vertical cavity surface emitting laser having a pair of reflecting mirrors and a medium layer including an active layer provided between the reflecting mirrors on a substrate,
A vertical cavity surface emitting laser characterized by having a constriction structure for confining a current formed by holes in the medium layer adjacent to one of the pair of reflecting mirrors.   2. The vertical cavity surface emitting laser according to claim 1, wherein the medium layer including the active layer is composed of GaN, AlN, InN, or a mixed crystal thereof.   2. The vertical cavity surface emitting laser according to claim 1, wherein the medium layer including the active layer is made of GaAs, AlAs, GaP, InP, or a mixed crystal thereof.   4. The vertical resonance according to claim 1, wherein at least one of the pair of reflection mirrors has a periodic structure having a refractive index with respect to a direction perpendicular to a resonance direction of light. Type surface emitting laser.   5. The vertical cavity surface emitting laser according to claim 1, wherein the hole has a thin ring shape in a plane parallel to the substrate.   6. The vertical cavity surface emitting laser according to claim 5, wherein the hole has a shape in which the thin ring shape has anisotropy.   5. The vertical cavity surface emitting laser according to claim 1, wherein the hole has a three-dimensional shape spreading in a light resonance direction.   8. The vertical cavity surface emitting according to claim 1, wherein the hole is a hole formed by internal processing with an ultrashort pulse laser in a medium layer including an active layer. laser.

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