JP2002329930A - Optical transmission/reception system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an optical transmission/reception system to be facilitated in a building by utilizing a surface emitting semiconductor laser element chip in which an operating voltage, an oscillation threshold value or the like can be lowered as a light emitting light source. SOLUTION: An n-type semiconductor distributed Bragg reflection mirror 3 is formed on an n-type GaAs substrate 2, and an n-type Gax In1-x Py As1-y layer 11 having a thickness of λ/4 is laminated thereon. A multiple quantum well active layer having an undoped lower GaAs spacer layer 4, active layers (quantum well active layers) 12 of three Gax In1-x As quantum well layers, and a GaAs barrier layer (20 nm) 13; and an undoped upper part GaAs spacer layer 4; are laminated thereon to form a resonator having a thickness (thickness of λ) of one wavelength of an oscillation wavelength λ in a medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser used for optical communication and the like, and an optical transmission / reception system therefor. The present invention relates to an optical transmission / reception system in which a plurality of laser elements are formed using a surface emitting laser to enable large-capacity communication.

[0002]

2. Description of the Related Art A surface emitting semiconductor laser emits laser light in a vertical direction from the surface of a substrate, so that two-dimensional parallel integration is possible, and the spread angle of the output light is relatively narrow (about 10 degrees). Therefore, it is easy to couple with an optical fiber and easy to inspect the element.
Therefore, in particular, development as an element suitable for configuring an optical transmission module (optical interconnection device) of a parallel transmission type has been actively conducted. The immediate application of the optical interconnection device is parallel connection between housings of computers and the like and between boards, as well as short-distance optical fiber communication, but large-scale computer networks and long distances are expected applications in the future. There is a trunk system for distance and large-capacity communication. Generally, a surface emitting semiconductor laser is made of GaAs or Ga.
Although it is common to comprise an active layer made of InAs, an upper semiconductor distributed Bragg reflector arranged above and below the active layer, and an optical resonator composed of a lower semiconductor distributed Bragg reflector on the substrate side. Since the length of the optical resonator is significantly shorter than that of the edge emitting semiconductor laser,
By setting the reflectivity of the reflecting mirror to an extremely high value (99% or more), it is necessary to easily cause laser oscillation. For this reason, a semiconductor distributed Bragg reflector formed by alternately laminating a low-refractive-index material made of AlAs and a high-refractive-index material made of GaAs at a period of １ ／ wavelength is usually used.

By the way, as described above, a long wavelength band laser having a laser wavelength of 1.1 μm or more used for optical communication, for example, a long wavelength band having a laser wavelength of 1.3 μm or 1.55 μm. In the laser, InP is used for the production substrate and InGaAsP is used for the active layer. However, the lattice constant of InP of the substrate is large, and a reflective mirror material matching the substrate cannot obtain a large refractive index difference. Must be more than pairs. Another problem with the semiconductor laser formed on the InP substrate is that the characteristics greatly change with temperature. For this reason, it is necessary to add a device for keeping the temperature constant, and it is difficult to use the device for general purposes such as consumer use. Light emitting semiconductors have not yet been put to practical use. As an invention made to solve such a problem, Japanese Patent Application Laid-Open No. 9-237942 has been proposed.
The one disclosed in Japanese Patent Application Laid-Open Publication No. H10-260, 1993 is known. According to this, a GaAs substrate is used as a production substrate, and a semiconductor layer made of AlInP that can be lattice-matched with the substrate is used as a low refractive index layer of at least one of the semiconductor distributed Bragg reflectors in the lower upper portion on the substrate side. G is applied to at least one of the lower and upper semiconductor distributed Bragg reflectors in the high refractive index layer.
The purpose of the present invention is to realize a semiconductor Bragg reflector having a high reflectivity with a small number of layers by using a semiconductor layer made of aInNAs so as to obtain a larger refractive index difference than before. GaInNAs is used as a material for the active layer. This is because the band gap (forbidden band width) can be reduced from 1.4 eV to 0 eV by increasing the N composition, and therefore, it can be used as a material that emits a wavelength longer than 0.85 μm. Because it becomes. In addition, it mentions that a semiconductor layer made of GaInNAs is preferable as a material for a long-wavelength surface emitting semiconductor laser in a 1.3 μm band and a 1.55 μm band because lattice matching with a GaAs substrate is possible.

[0004] However, in the past, only suggesting the possibility of realizing a surface emitting semiconductor laser in a wavelength band longer than 0.85 µm, such a thing has not been actually realized. This is because, although the basic configuration is almost theoretically determined, a more specific configuration for actually obtaining stable laser emission is still unknown. As an example, as described above, Al
A semiconductor distributed Bragg reflector formed by alternately laminating a low-refractive-index material composed of As and a high-refractive-index material composed of GaAs at a period of 1/4 wavelength;
Alternatively, as disclosed in Japanese Unexamined Patent Publication No. 9-237942, a semiconductor distributed Bragg reflector using a low refractive index layer made of a semiconductor layer made of AlInP that can be lattice-matched with the substrate has no laser element. No light was emitted, or even if light was emitted, its luminous efficiency was low, far from a practical level. This is because a material containing Al is chemically very active and crystal defects caused by Al are likely to occur. To solve this problem, Japanese Patent Application Laid-Open Nos. 8-340146 and 7-307 disclose the method.
There is a proposal for forming a semiconductor distributed Bragg reflector from GaInNP and GaAs that do not contain Al as in the invention disclosed in Japanese Patent No. 525. However, GaInNP
The refractive index difference between AlAs and GaAs is about half the refractive index difference between AlAs and GaAs. That is, at present, optical fiber communication is expected in computer networks and the like.
There is no long-wavelength surface-emitting semiconductor laser having a wavelength of 1.7 μm and a communication system using the same.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has a laser oscillation wavelength of 1.
1. Field of the Invention The present invention relates to a long-wavelength surface emitting semiconductor laser having a wavelength of 1 μm to 1.7 μm and an optical transmission / reception system thereof. The purpose of the present invention is to make it easy to construct such an optical transmission / reception system in a building. The second object is that the laser oscillation wavelength that can be used stably is 1.1 μm or more.
An object of the present invention is to make it easy to construct such an optical transmission and reception system in a building by using a long-wavelength band surface emitting semiconductor laser device chip of 1.7 μm as a light emitting light source. Further, a third object is to propose a specific method for easily constructing such an optical transmission / reception system.

[0006]

According to the present invention, in order to solve the above-mentioned problem, an oscillation wavelength of 1.1 μm to 1.1 μm is required.
1.7 μm, and the main element of the active layer that generates light is a layer made of Ga, In, N, or As, or Ga, I
A surface-emitting type semiconductor laser device chip having a resonator structure including a reflecting mirror provided above and below the active layer to obtain a laser beam, wherein the reflecting mirror is formed of n and As. A semiconductor distributed Bragg reflecting mirror in which, when the reflection wavelength is 1.1 μm or more, the refractive index of a material layer constituting the reflecting mirror changes periodically to a value different from each other, and reflects incident light by light wave interference; The material layer having a small refractive index is Al _x Ga _1-x As (0 <x ≦ 1), and the material layer having a large refractive index is Al _y Ga _1-y As (0 ≦ y <x ≦).
1), and and the the refractive index between the refractive index is small and large material layer has a value between the small and large _{Al z Ga 1-z As (} 0
≦ y <z <x ≦ 1)
A surface-emitting type semiconductor laser device chip such as a reflecting mirror provided with a thickness of 0 nm to 50 nm is used as a light emitting source, and an optical fiber transmission line for transmitting an optical signal to the light emitting source is optically coupled. In an optical transmitting and receiving system provided with a light receiving unit optically coupled to the side opposite to the light emitting light source of the transmission path, the optical transmitting and receiving system is a premises optical transmitting and receiving system for performing communication inside the building, Installing the light emitting light source at a first point in the building, and installing the light receiving unit at a second point in the building;
A reflection member for changing the direction of the transmission path is provided between the first point and the second point.

[0007] In the field of laser oscillation wavelength of 1.1 µm to 1.7 µm band where optical fiber communication is expected, such as computer networks and trunk lines of long-distance large-capacity communication, it is possible to reduce the operating voltage, oscillation threshold current, and the like. However, there has been no surface emitting semiconductor laser capable of generating stable oscillation with little heat generation of the laser element and an optical transmitting and receiving system using the same. In addition, the oscillation threshold current and the like can be reduced, and stable oscillation can be performed with less heat generated by the laser element, and a low-cost and practical building (premises) optical transmission / reception system can be realized. Further, when constructing such an optical premise transmission / reception system, a reflection member for changing the direction of the transmission line is provided, so that the transmission line can be efficiently arranged according to the shape of the building, and unnecessary The transmission line is not exposed to the eyes, and the transmission line does not occupy more area than necessary in the ceiling, under the floor, or inside the wall. The degree of freedom has increased. According to this invention, by devising the semiconductor distributed Bragg reflector, the operating voltage, the oscillation threshold current, and the like can be reduced, the laser element generates less heat, and stable oscillation can be achieved. (Premise) Optical transmission / reception system was realized.
Further, when constructing such an optical premise transmission / reception system, a reflection member for changing the direction of the transmission line is provided, so that the transmission line can be efficiently arranged according to the shape of the building, and unnecessary The transmission line is not exposed to the eyes, and the transmission line does not occupy more area than necessary in the ceiling, under the floor, or inside the wall. The degree of freedom has increased.

According to a second aspect of the present invention, the oscillation wavelength ranges from 1.1 μm to 1.
7 μm, and the main element of the active layer that generates light is G
a, In, N, As layer, or Ga, In,
A surface-emitting type semiconductor laser device chip having a resonator structure including a reflecting mirror provided above and below the active layer for obtaining a laser beam, wherein the reflecting mirror has a reflection wavelength. Is greater than or equal to 1.1 μm, the refractive index of the material layer constituting the reflecting mirror periodically changes to a value that is small and large,
A semiconductor distributed Bragg reflector for reflecting incident light by light wave interference, and the material layer having a small refractive index is made of Al.
_x Ga _1-x As and (0 <x ≦ 1), the material layer of the refractive index is large is a reflective mirror which is a _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), the active layer the main composition between reflector _Ga and _{x in 1-x P y as} 1-y (0 <x ≦
1,0 <y ≦ 1) A surface-emitting type semiconductor laser device chip provided with a non-radiative recombination prevention layer composed of a layer is used as a light-emitting light source, and an optical fiber transmission line for transmitting an optical signal to the light-emitting light source is optically connected. In the optical transmitting and receiving system provided with a light receiving unit optically coupled to the opposite side of the transmission path and the light emitting light source,
The optical transmitting and receiving system is a premises optical transmitting and receiving system for performing communication inside the building, wherein the light emitting light source is installed at a first point in the building, and the light receiving unit is installed at a second point in the building, A reflection member for changing the direction of the transmission path is provided between the first point and the second point.

In the field of laser oscillation wavelengths of 1.1 μm to 1.7 μm where optical fiber communication is expected, such as computer networks and trunk lines for long-distance large-capacity communication, long-wavelength surface light emission can be used stably. Although a semiconductor laser and an optical transmission / reception system using the same did not exist, stable oscillation can be achieved by using a surface emitting semiconductor laser device chip provided with a non-emitting recombination prevention layer as in the present invention. Thus, a practical optical transmission / reception system using this as a light emitting light source was realized. Furthermore, in constructing such an optical transmission / reception system within a premises, a reflection member for changing the direction of the transmission line is provided, so that the transmission line can be efficiently arranged according to the shape of the building, which is unnecessary. The transmission line is not exposed to the eyes, and the transmission line does not occupy more area than necessary in the ceiling, under the floor, or inside the wall. The degree of freedom has increased.
According to this invention, stable oscillation can be achieved by using a surface emitting semiconductor laser device chip provided with a non-radiative recombination preventing layer, and a practical optical transmission / reception system using this as a light emitting light source can be realized. . Furthermore, in constructing such a local optical transmission / reception system, a reflection member for changing the direction of the transmission line is provided, so that the transmission line can be efficiently arranged according to the shape of the building,
This makes it possible to design buildings effectively, without unnecessary transmission lines being exposed to the eyes and unnecessary transmission lines occupying the ceiling, under the floor, or inside the walls. The degree of freedom in aesthetic design has increased.

According to a third aspect of the present invention, the reflection member converts the direction of the transmission path by 90 °. In such an in-premises transmission / reception system, the reflection member for changing the direction of the transmission line changes the direction of the transmission line by 90 °, so that the transmission line can be efficiently arranged according to the shape of the building. . Usually, when designing / constructing a building, its columns,
The walls, floor, and ceiling are designed / constructed based on straight lines and planes intersecting the straight lines at 90 °. Therefore, the transmission path of the optical transmission / reception system such as the present invention that is stretched inside the building also changes by 90 ° according to the pillar, wall, floor, ceiling, etc. of the building when the direction of the transmission path is changed. It is most efficient to do so and the arrangement of the transmission lines is beautiful. Thus, since the reflecting member for changing the direction of the transmission line changes the direction of the transmission line by 90 ° in this way, unnecessary transmission lines are exposed where they can be seen, or the ceiling, floor, or wall of a building can be exposed. The transmission line does not occupy the area more than necessary inside, and the building design can be effectively performed, and the degree of freedom to the aesthetic design has increased. According to this technical means, the reflecting member for changing the direction of the transmission line changes the direction of the transmission line by 90 °, so that the transmission line can be efficiently arranged according to the shape of the building.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are not merely intended to limit the scope of the present invention but are merely illustrative examples unless otherwise specified. . First, the laser oscillation wavelength with a small transmission loss, which is a light emitting element applied to the optical communication system of the present invention, is as follows.
One example of a long-wavelength band surface emitting semiconductor laser of 1 μm to 1.7 μm will be described with reference to FIG. As described above, conventionally, the laser oscillation wavelength to be applied by the present invention is 1.
With respect to the long-wavelength surface emitting semiconductor laser having a wavelength of 1 μm to 1.7 μm, there is only a suggestion of the possibility, and a material for realizing the laser, and a more specific and detailed configuration were unknown. In the present invention, a material such as GaInNAs is used for the active layer, and a more specific configuration is clarified. The details are described below.

In the present invention, n-Ga having a (100) plane orientation is used.
Oscillation wavelength λ in each medium on As substrate 2
N-Al with a thickness of 1/4 (thickness of λ / 4)_xGa
_1-xAs (x = 1.0) (low refractive index layer to low refractive index
Layer) and n-Al_yGa_1-yAs (y = 0) (high refractive index
N-semiconductor in which 35 layers are alternately stacked with each other
Body distribution Bragg reflector 3 (AlAs / GaAs lower semiconductor)
And a λ / 4 thick layer on it.
Sano n-Ga_xIn_1-xP_yAs_1-y(X = 0.
5, y = 1) Layer 11 was laminated. In this example, n-Ga_x
In_1-xP_yAs_{1 -Y}(X = 0.5, y = 1) layer
A part of the lower reflector, a low refractive index layer (low refractive index layer)
Has become. And undoped lower GaAs
Pacer layer 4 and three layers of Ga_xIn_{1 -X}As quantum well layer
Active layer (quantum well active layer) 12 and GaAs barrier
A multiple quantum well active layer comprising a layer (20 nm) 13;
And an upper doped GaAs spacer layer,
Of the thickness of one oscillation wavelength λ (thickness of λ)
A resonator is formed. In addition, C (carbon)
P-Ga_xIn_1-xP_yAs_1-y(X = 0.
5, y = 1) layer and Zn-doped p-Al_xGa_1-xAs
(X = 0) is set to 1 of the oscillation wavelength λ in each medium.
/ 4 times the thickness of the periodic structure (one cycle) laminated alternately
Layer on which C-doped p-Al_xGa_1-xAs
(X = 0.9) and Zn-doped p-Al_xGa_1-xAs
(X = 0) is set to 1 of the oscillation wavelength λ in each medium.
With a periodic structure (25 periods) alternately stacked with a thickness of / 4 times
Semiconductor Bragg reflector 5 (Al_0.9Ga
_0.1As / GaAs upper semiconductor distributed Bragg reflector)
Is formed. In this example, p-Ga_xIn_1-xP _y
As_1-yThe (x = 0.5, y = 1) layer is also a part of the upper reflecting mirror.
And a low refractive index layer (a layer having a low refractive index).
Here, both the upper and lower mirrors have low refractive index layers.
(Low refractive index layer) / high refractive index layer (high refractive index layer) alternately
In the present invention, there is a refraction
Al with a ratio between small and large_zGa_1-zAs (0 ≦
providing a hetero-spike buffer layer consisting of y <z <x ≦ 1)
ing.

FIG. 2 shows a surface emitting semiconductor device applied to the present invention.
Reflector whose reflection wavelength of body laser is 1.1μm or more
This will be described more specifically. The reflection wavelength applied to the present invention is
In a reflecting mirror of 1.1 μm or more, a low refractive index layer (a low refractive index layer) is used.
Layer) and the high refractive index layer (high refractive index layer)
Hetero spike buffer layer Al with a value between_zGa
_1-zAs (0 ≦ y <z <x ≦ 1) 15 is provided.
Figure 2 shows a part of a semiconductor distributed Bragg reflector.
There is a figure (it is omitted in FIG. 1 because the figure is complicated)
are doing). Conventional semiconductor with laser wavelength 0.85μm band
With respect to the laser, such a heterospike buffer layer 15
It is being considered to establish
The material, its thickness, etc.
It has not been. Also, the laser oscillation wavelength as in the present invention is
1.1 μm to 1.7 μm long wavelength band surface emitting semiconductor laser
Is not considered at all. The reason is this field
(Long wavelength band whose laser oscillation wavelength is 1.1 μm to 1.7 μm
Surface emitting semiconductor lasers) is a new field, and it is still almost
This is because research has not progressed. The inventor is quick
In this field (the laser oscillation wavelength is 1.1 μm to 1.7 μm)
Long wavelength surface emitting semiconductor laser and optical communication using the same
Of the usefulness of shin) and intensive study to realize it
Was done.

In such a hetero spike buffer layer, the refractive index of the material layer is changed continuously or step by changing the Al composition continuously or stepwise by controlling the gas flow rate at the time of formation. It is formed as follows. More _{specifically, Al z Ga 1-z As} (0
.Ltoreq.y <z <x.ltoreq.1) The layer is formed so that the value of z changes from 0 to 1.0, that is, the ratio of Al to Ga gradually changes, such as GaAs to AlGaAs to AlAs. This is created by controlling the gas flow during layer formation as described above. Further, it may be formed so that the ratio of Al and Ga changes continuously as described above, or the same effect can be obtained even if the ratio changes stepwise. The reason for providing such a heterospike buffer layer is to solve the problem that the electrical resistance of the p-semiconductor distributed Bragg reflector, which is one of the problems of the distributed Bragg reflector, is high. This is due to a hetero-barrier generated at the interface between the two types of semiconductor layers constituting the semiconductor distributed Bragg reflector. As the Al composition gradually changes to the other composition,
By changing the refractive index, it is possible to suppress the generation of the hetero barrier. Such a hetero spike buffer layer will be described more specifically. FIG. 3 shows an example of a semiconductor distributed Bragg reflector in which a hetero-spike buffer layer is provided between two types of semiconductor layers constituting the semiconductor distributed Bragg reflector. In the figure, as an example of the material of the semiconductor distributed Bragg reflector, an AlGaAs-based semiconductor material (Al _z
Ga _1-z As (0 ≦ y <z <x ≦ 1) is shown. The two kinds of semiconductor layers constituting the semiconductor distributed Bragg reflector are AlAs and GaAs, and AlAs and Ga
As a hetero-spike buffer layer having an intermediate valence band energy of As, a composition gradient layer in which the Al composition is changed is provided therebetween. _That, Al _{z Ga 1-z} As
(0 ≦ y <z <x ≦ 1) The value of z of the layer is changed from 0 to 1.0, that is, GaAs to AlGaAs to AlA.
The ratio of Al and Ga is gradually changed to s. The AlGaAs-based semiconductor material has an increased bandgap energy and a reduced refractive index as the Al composition increases. At this time, in the conduction band, the energy starts to decrease until the Al composition reaches 0.43, but in the valence band, the valence band energy decreases monotonically in substantially proportion to the increase amount of the Al composition ( Overall, the bandgap energy increases with composition.) In addition to this, when an AlGaInP-based material is taken as an example, this material is a quaternary material, but shows the same tendency as the AlGaAs-based Al composition increases as the AlInP composition increases. The conduction band energy begins to decrease after increasing to an AlInP composition of 0.7. However, the valence band energy similarly decreases monotonically with increasing AlInP composition.

In the example shown in FIG. 3, the composition gradient (band-gap energy increase rate) of the region near the GaAs layer (region I in FIG. 3) is calculated by comparing the composition gradient rate (band-gap energy increase rate) of the region near the AlAs layer (FIG. 3).
In region II), the composition gradient is larger than the composition gradient. For comparison, FIG. 4 shows a structure in which a linear composition gradient layer having a linearly changed Al composition is used as a hetero-spike buffer layer.
FIG. 5 shows the results of estimating the electrical resistance of a 4-pair p-DBR in which the heterospike buffer layer of FIG. In FIG. 5, the carrier density of each layer of the DBR including the hetero-spike buffer layer is a P-type of 1E18 [cm ⁻³ ], and the vertical axis indicates the differential sheet resistance near zero bias. The abscissa indicates the Al composition gradient in the region I, and indicates the thickness of the different region I (shown in the figure). The sum of area I and area II is always 20n
m, and the thickness and the composition gradient of the region II are determined by the thickness and the composition gradient of the region I. Simply GaAs layer and AlA
When the linear composition gradient layer is provided between the s layers, the Al composition gradient is 0.05 [nm ^-1 ], which corresponds to the point A in the figure. As shown in FIG. 5, by increasing the gradient of the Al composition in the region I, the resistance value is reduced as compared with the conventional case where the composition gradient is simply made linear. It can also be seen that there is an optimum Al composition gradient that is minimal. For example, when the thickness of the region I is 10 nm (the same thickness as that of the region II), the Al composition gradient is 0.09 [nm ^-1 ], and the resistance is reduced to about 80% of the conventional resistance. It does not depend on voltage.)

Next, the reason will be described. FIG.
FIG. 3 is a band diagram of a thermal equilibrium state of a DBR hetero interface made of AlAs / GaAs. As shown in the figure, heterospikes caused by band discontinuity mainly appear remarkably on the AlAs layer side having a large band gap, and almost no notch is generated on the GaAs layer side. The notch generated on the GaAs layer side does not originally cause a high resistance, so that the AlA
It is important to lower the resistance efficiently that spikes generated on the s layer side are efficiently flattened with a limited thickness of the hetero spike buffer layer. In the structure of FIG.
This corresponds to the fact that the composition is rapidly increased on the aAs side and the composition gradient on the AlAs side where spikes occur is gradually changed. This makes it possible to reduce the occurrence of spikes as compared with the case where the composition change of the hetero-spike buffer layer is simply linear (accordingly, when the Al composition gradient in the region I is smaller than that in the region II, the resistance value becomes smaller). Increases.). FIG. 7 is a schematic diagram of a band diagram in the thermal equilibrium state of FIG. Compared to the conventional simple composition gradient layer, A
The composition gradient on the lAs side can be reduced. From the above, it is understood that the electric resistance can be reduced as compared with the related art by increasing the composition gradient in the region I.

Next, such a refractive index has a value between a small value and a large value.
Hetero spike buffer layer Al_zGa_1-zAs (0 ≦
y <z <x ≦ 1)
explain. FIG. 8 shows A having a reflection center wavelength at 1.3 μm.
For a 4-pair DBR with lAs / GaAs,
By changing the thickness of the spike buffer layer,
It is the result of having calculated the partial electrical resistivity. DBR layer dopi
Ring density is 1E18cm^{− 3}And heterospike buffering
The doping density of each layer including the layer is uniform. Ma
The value shown by the broken line is obtained from the bulk resistance of each semiconductor layer.
If the resistivity is assumed to be
It shows the resistivity of the DBR obtained in this case. FIG.
DBR without hetero spike buffer layer
When the spike buffer layer thickness is 0), the resistivity is 1Ωcm²And non
Always high resistance, more than 20 pairs as a practical problem
It is difficult to energize the element through the layered DBR itself.
Requires a very high voltage to further energize
You. Therefore, a surface emitting laser device having such a DBR
Is difficult to actually oscillate. However, 5
When a hetero spike buffer layer of nm
Compared to the case without the spike buffer layer, the resistance is about two digits.
It is possible to reduce the drag coefficient, making it easier to energize the element.
Therefore, it is possible to obtain oscillation. In addition, the electricity required for
Pressure also reduces the reliability of the device,
Problems are greatly improved. In addition, heterospike buffer
As the thickness of the layer increases, the resistivity decreases sharply.
Above 20 nm, the resistivity has a substantially constant value. Figure
8 is a hetero-spike buffer layer and p-type doping of each layer
Density 1E18cm ^-3As a uniform doping
It shows the structure. Note that this doping
The concentration is a standard value usually used for DBR. FIG.
In the structure of DBR, the decrease in resistivity begins to saturate
The thickness of the spike buffer layer is about 20 nm.
The resistivity is very low, about 2.5 times the bulk resistivity.
Has been reduced to a lower value. In other words, the terror spike buffer layer
If the lower limit of the thickness is 20 nm,
The operating voltage of the element can be set to the lowest value,
Heat can also be minimized. Therefore, oscillation can be maintained
Temperature, as well as the resulting light output.

However, the optical characteristics of the DBR, on the other hand, have a problem that the reflectance decreases as the thickness of the heterospike buffer layer increases. FIG. 9 shows in detail how the reflectivity of the DBR decreases with the change in the thickness of the hetero-spike buffer layer. As compared with the straight line shown in the figure, it can be seen that the rate of change in reflectance sharply increases from the thickness of the hetero-spike buffer layer of 50 nm or more.
The oscillation threshold current of the device starts to increase correspondingly sharply. Therefore, the upper limit of the thickness of the hetero spike buffer layer is 50.
nm is appropriate. As described above, 20 nm or more,
In a DBR provided with a hetero-spike buffer layer of 50 nm or less, the resistance due to the influence of the hetero interface can be effectively reduced, and a high reflectance can be obtained at the same time. In a surface emitting laser device using this, it is possible to easily obtain oscillation at a low threshold current under realistic driving conditions.

The laser oscillation wavelength of the present invention is 1.1 μm.
m to 1.7 μm long wavelength band surface emitting semiconductor laser,
The thickness is preferably from 20 nm to 50 nm. If the thickness is smaller than this, there is a problem that the resistance becomes large and current does not easily flow, the element generates heat, and the driving energy increases. When the thickness is large, the resistance becomes small, which is advantageous in terms of heat generation of the element and driving energy. However, there is a problem that the reflectance cannot be obtained this time, and as described above, the optimum range (20 nm to 5 nm) is obtained.
(Thickness of 0 nm). As described above, the provision of such a hetero-spike buffer layer for a conventional semiconductor laser having a laser wavelength in the 0.85 μm band has been studied.
In the case of a long-wavelength surface emitting semiconductor laser of 1 μm to 1.7 μm, it is more effective. This is because, for example, to obtain the same reflectance (for example, 99.5% or more), 0.85
In the case of the 1.1 μm to 1.7 μm band than the μm band, such a material layer can be approximately doubled, so that the resistance value of the semiconductor distributed Bragg reflector can be reduced and the operating voltage can be reduced. In addition, the oscillation threshold current and the like are reduced, which is advantageous in terms of prevention of heat generation of the laser element, stable oscillation, and low energy driving. In other words, providing such a hetero-spike buffer layer on a semiconductor distributed Bragg reflector is particularly effective for a long-wavelength surface emitting semiconductor laser having a laser oscillation wavelength of 1.1 μm to 1.7 μm as in the present invention. It can be called a device. As an example of a more detailed study result for obtaining an effective reflectance, for example, in a 1.3 μm band surface emitting laser device, Al _x Ga _1-x As (x = 1.0) (low refractive index) rate layer-refractive index small layer) and _{Al y Ga 1-y as (} y
= 0) (in the case of a high refractive index layer-refractive index large layer) 20 period stacking, the reflectance of the semiconductor distributed Bragg reflector is 99.7% or less _{Al z Ga 1-z As (} 0 ≦ y
<Z <x ≦ 1) The thickness of the layer is 30 nm. The wavelength band where the reflectance is 99.5% or more is 53 nm,
When the reflectance is designed to be 99.5% or more, it is only necessary to control the film thickness by ± 2%. Therefore, when prototypes of 10 nm, 20 nm, and 30 nm which are equivalent to and thinner than this were prototyped, the reflectivity could be kept to a practically acceptable level, and the resistance value of the semiconductor distributed Bragg reflector could be reduced. A 1.3 μm band surface emitting laser device was realized, and laser oscillation was successful. Other configurations of the prototyped laser element are as described below. In the multilayer reflector, there is a band having a high reflectivity including the design wavelength (assuming that the film thickness can be completely controlled). It is referred to as a high-reflectance band (including a region where the reflectivity is equal to or more than a required value for a target wavelength).
This is the region where the reflectance at the design wavelength is the highest and decreases very little as the wavelength increases. It drops off sharply from some area. Originally, it is necessary to completely control the film thickness of the multilayer mirror at the atomic layer level so that the reflectance is higher than the required reflectance for the target wavelength. However, a film thickness error of about ± 1% actually occurs, so that the target wavelength deviates from the wavelength having the highest reflectance. For example, when the target wavelength is 1.3 μm, when the film thickness control is shifted by 1%,
The wavelength with the highest reflectance is shifted by 13 nm. Therefore, it is desirable that the band of the high reflectance (here, the region where the reflectance is equal to or more than a required value with respect to a target wavelength) is wide. Thus, the laser oscillation wavelength as in the present invention is 1.1 μm to
In a long-wavelength surface emitting semiconductor laser of 1.7 μm, by devising and optimizing the configuration of such a semiconductor distributed Bragg reflector, it is possible to reduce the resistance value while maintaining a high reflectivity. Voltage, oscillation threshold current, and the like can be reduced, and heat generation of the laser element can be prevented, and stable oscillation and low-energy driving can be performed.

Returning again to FIG. 1, the uppermost p-Al _x G
The a1 _- xAs (x = 0) layer also has a role as a contact layer (p-contact layer) for making contact with an electrode. Here, the In composition x of the quantum well active layer was 39% (Ga _0.61 In _0.39 As). The thickness of the quantum well active layer was 7 nm. The quantum well active layer had a compressive strain of about 2.8% with respect to the GaAs substrate. The entire surface emitting semiconductor laser was grown by MOCVD. In this case, no lattice relaxation was observed. The raw materials constituting each layer of the semiconductor laser include:
TMA (trimethylaluminum), TMG (trimethylgallium), TMI (trimethylindium), As
H ₃ (arsine) and PH ₃ (phosphine) were used.
H ₂ was used as a carrier gas. In the case where the strain is large as in the active layer (quantum well active layer) of the device shown in FIG. Here, Ga
The InAs layer (quantum well active layer) is grown at 550 ° C. The MOCVD method used here has a high degree of supersaturation and is suitable for crystal growth of a high strain active layer. In addition, high vacuum is not required as in the MBE method, and the supply flow rate and supply time of the source gas may be controlled.

In this example, a portion outside the current path was formed by irradiating protons (H ⁺ ) to form an insulating layer (high resistance portion) to form a current narrowing portion. In this example, a p-side electrode is formed on the p-contact layer which is the uppermost layer of the upper reflector and is a part of the upper reflector, excluding the light emitting portion, and an n-side electrode is formed on the back surface of the substrate. Was formed. In this example, in the active region (resonator including the upper and lower spacer layers and the multiple quantum well active layer in this embodiment) sandwiched between the upper and lower reflectors and into which carriers are injected and recombined, the active region has material containing al (percentage of group III 1% or more) without using a further layer closest to the active layer of the low refractive index layer of the lower and upper reflector _{Ga x in 1-x P y} As
_1-y (0 <x ≦ 1, 0 <y ≦ 1) as a non-radiative recombination preventing layer. That is, by appropriately selecting the value of x or y, GaInP, GaInPAs, or GaPAs is used as the non-radiative recombination preventing layer. Note that this layer, there is a case where a material other than Al is added small amount, the main _{material, Ga x In 1-x P} y As
_1-y (0 <x ≦ 1, 0 <y ≦ 1). The carriers are confined between the low-refractive index layers of the upper and lower reflectors, which are the wide gaps closest to the active layer, so that only the active region is an Al-free layer (1% of the group III).
However, if the low refractive index layer (wide gap layer) of the reflector in contact with the active region is made to contain Al even when the carrier is injected and recombined, non-radiative recombination occurs at this interface. Occurs and the luminous efficiency is reduced. Therefore, it is desirable that the active region be formed of a layer containing no Al. Also this main composition _{Ga x In 1-x P y} As
_The non-radiative recombination preventing layer made of _1-y (0 <x ≦ 1, 0 <y ≦ 1) has a lattice constant smaller than that of the GaAs substrate and has a tensile strain. In the epitaxial growth, the growth is performed by reflecting the information of the base, and if there is a defect on the surface of the substrate, it goes up to the growth layer. However, it is known that the presence of a strained layer is effective in preventing such defects from climbing. When the defects reach the active layer, the luminous efficiency is reduced. In the case of an active layer having a strain, there arises a problem that the critical thickness is reduced and a layer having a required thickness cannot be grown. In particular, when the amount of compressive strain of the active layer is large, for example, 2% or more, or when the thickness of the strained layer is larger than the critical thickness, even if non-equilibrium growth such as low-temperature growth is performed, growth cannot be performed due to the presence of defects. This is particularly problematic. If a strained layer is present, such a defect can be prevented from climbing up, so that the luminous efficiency can be improved, a layer having a compressive strain of 2% or more of the active layer can be grown, or the thickness of the strained layer can be reduced to a critical film. It becomes possible to grow thicker than thick.

This Ga_xIn_1-xP_yAs_1-y(0
<X ≦ 1, 0 <y ≦ 1) layer is in contact with the active region and is active
It also has the role of confining carriers in the region,
_xIn_1-xP_yAs_1-y(0 <x ≦ 1, 0 <y ≦
1) The band gap energy of the layer decreases as the lattice constant decreases.
It can take large amounts of lugi. For example, Ga_xIn_1-xP
In the case of (y = 1), x increases and approaches GaP.
Increase the lattice constant and the band gap.
You. The band gap Eg is Eg (Γ) =
1.351 + 0.643x + 0.786x², Indirect transition
And Eg (X) = 2.24 + 0.02x
You. Therefore, the active region and Ga_xIn_1-xP_yAs _1-y
(0 <x ≦ 1, 0 <y ≦ 1) layer has a large hetero barrier.
As a result, carrier confinement is improved and threshold current is reduced.
This has the effect of reducing the temperature and improving the temperature characteristics. Furthermore, this Ga_x
In_1-xP_yAs_1-y(0 <x ≦ 1, 0 <y ≦ 1)
The non-radiative recombination prevention layer composed of a layer has a lattice constant of Ga.
Larger than the As substrate, having a compressive strain, and
When the lattice constant of the active layer is Ga_xIn_1-xP_yAs_1
-Y(0 <x ≦ 1, 0 <y ≦ 1) Larger compressive strain than layer
have. In addition, this Ga_xIn_1-xP_yAs
_1-y(0 <x ≦ 1, 0 <y ≦ 1) The direction of strain in the layer is active
Substantial compressive strain perceived by the active layer because it is in the same direction as the layer
Work in the direction of reducing The larger the distortion, the more the influence of external factors
The active layer has a compressive strain of 2% or more, for example.
Is particularly effective when the thickness is large or when the thickness exceeds the critical thickness.
You. For example, a surface emitting laser with an oscillation wavelength of 1.3 μm band
It is preferably formed on a GaAs substrate.
In many cases, a conductor multilayer reflector is used, and the total thickness is
Before growing the active layer, 50 to 80 semiconductor layers of 5 to 8 μm are formed.
Need to be grown (while edge-emitting lasers,
The total thickness before growing the active layer is about 2 μm and about 3 layers.
It is only necessary to grow a semiconductor layer). In this case, high quality
Various causes (even once occurred
Defects basically creep up in the crystal growth direction,
Surface defects on the GaAs substrate
What is the defect density of the surface just before the active layer growth compared to the depression density?
Even if it increases. Insertion of strained layer before active layer growth
In addition, when the effective compressive strain perceived by the active layer is reduced,
To reduce the effect of defects on the surface just before the growth of the conductive layer
become. In this example, in the active area and the mirror and the active area
Since the interface with Al does not contain Al, the carrier injection
Non-light emission due to crystal defects caused by Al when entering
There was no recombination and non-radiative recombination was reduced.

As mentioned above, the interface between the reflector and the active region
In which Al does not contain, that is, non-radiative recombination prevention
The provision of a stop layer can be applied to both upper and lower reflectors.
Although preferred, it is effective to apply it to one of the mirrors.
You. In this example, both the upper and lower reflectors are semiconductor distribution black.
Mirror, but one of the mirrors is a semiconductor distributed Bragg
It is also possible to use a reflecting mirror and the other reflecting mirror as a dielectric mirror
No. In the above-described example, the most active layer of the low refractive index layer of the reflecting mirror is used.
Only the layer close to_xIn_1-xP_yAs_1-y(0 <
x ≦ 1, 0 <y ≦ 1)
Has a plurality of layers of Ga _xIn_1-xP_yAs_1-y(0 <x
≦ 1, 0 <y ≦ 1) may be used as the non-radiative recombination preventing layer.
No. Further, in this example, the distance between the GaAs substrate and the active layer is
Applying this idea to the lower reflector, there is a problem when growing the active layer
The crawling of crystal defects caused by Al onto the active layer
The adverse effect of the active layer is suppressed and the active layer is crystallized with high quality.
Can be lengthened. Due to these, luminous efficiency is high,
A surface emitting semiconductor laser with sufficient reliability for practical use can be obtained.
Was. In addition, the low refractive index layer of the semiconductor distributed Bragg reflector is
Not all but at least the part closest to the active area
Ga not containing l_xIn_1-xP_yAs _1-y(0 <x
≦ 1, 0 <y ≦ 1)
The above effect can be obtained without particularly increasing the number.
coming.

The oscillation wavelength of the surface emitting semiconductor laser manufactured in this manner was about 1.2 μm. GaInAs on a GaAs substrate has a longer wavelength due to an increase in the In composition, but with an increase in the amount of strain. Conventionally, up to 1.1 μm has been considered to be the limit of a longer wavelength (see “IEEE Photonics. Tec”).
hnol. Lett. Vol. 9 (1997) pp. 1319-1321 "). However, as produced by the inventor of the present invention, a high strain GaI is formed by a high non-equilibrium growth method such as low temperature growth of 600 ° C. or less.
The nAs quantum well active layer can be grown coherently thicker than before, and the wavelength can reach 1.2 μm. This wavelength is transparent to the Si semiconductor substrate. Therefore, light transmission through the Si substrate becomes possible in a circuit chip in which an electronic element and an optical element are integrated on the Si substrate. As is apparent from the above description, by using GaInAs having a large In composition and a high compression strain for the active layer, G
It has been found that a long-wavelength surface emitting semiconductor laser can be formed on an aAs substrate. As described above, such a surface emitting semiconductor laser can be grown by MOCVD, but other growth methods such as MBE can also be used. Although the triple quantum well structure (TQW) has been described as an example of the stacked structure of the active layer, a structure (SQW, MQW) using a quantum well of another number of wells may be used. The structure of the laser may be another structure. Although the length of the resonator is set to the thickness of λ, it can be set to an integral multiple of λ / 2. Desirably, it is an integral multiple of λ. Although the example using GaAs as the semiconductor substrate has been described, the above concept can be applied to a case where another semiconductor substrate such as InP is used. The period of the reflecting mirror may be another period. In this example, an example in which the main element is a layer composed of Ga, In, and As, that is, Ga _x In _1-x As (GaInAs active layer) is shown as an active layer. Means that N is added and the main elements are Ga, In, N, A
s (GaInNAs active layer).
By actually changing the composition of the GaInNAs active layer, it was possible to perform laser oscillation in each of the 1.3 μm band and the 1.55 μm band. By examining the composition, a surface emitting laser having a longer wavelength, for example, in the 1.7 μm band can be obtained. In addition, GaAsS is used for the active layer.
Even if b is used, a 1.3 μm band surface emitting laser can be realized on a GaAs substrate. Thus, the wavelength of 1.1 μm to 1.7 μm
The conventional semiconductor laser has no suitable material, but the active layer has a high strain of GaInAs, GaInNAs, or GaAsS.
b and the provision of the non-radiative recombination preventing layer, wavelengths of 1.1 μm to 1.
In the long wavelength region of the 7 μm band, a high-performance surface emitting laser can be realized.

Next, the present invention is applied to the optical transmitting / receiving system of the present invention.
Other long-wavelength surface-emitting semiconductor lasers
The configuration will be described with reference to FIG. Again, figure
N-GaAs substrate having a plane orientation of (100) as in the case of 1.
21 is used. Oscillation wave in each medium
N-Al with a thickness 1/4 times the length λ (thickness of λ / 4)_xG
a_1-xAs (x = 0.9) and n-Al_xGa_1-xA
n-semiconductor distribution in which s (x = 0) is alternately stacked for 35 periods
Bragg reflector 24 (Al _0.9Ga_0.1As / Ga
As lower reflector), and a λ / 4-thick n is formed thereon.
-Ga_xIn_1-xP_yAs_1-y(X = 0.5, y =
1) Layers were laminated. In this example, n-Ga_xIn_1-xP
_yAs_1-yThe (x = 0.5, y = 1) layer is also the lower reflector
It is a part and is a low refractive index layer. And on top of that,
Undoped lower GaAs spacer layer 23 and three Ga layers
_xIn_1-xN_yAs_1-yActive layer 3 which is a quantum well layer
3 (quantum well active layer) and GaAs barrier layer 34 (15n
m) of the multi-quantum well active layer (3 in this example)
Quantum well (TQW)) and undoped upper GaAs
An oscillation wavelength in the medium is formed by laminating the
A resonator having a thickness of one wavelength (thickness of λ) is formed.
You. In addition, a p-semiconductor distributed Bragg reflector
(Upper reflector) 24 is formed. The upper reflector is
The AlAs layer 27 serving as the selectively oxidized layer is formed as a GaInP layer.
Low refractive index layer having a thickness of 3λ / 4 sandwiched between AlGaAs layers
(C-doped p-Ga having a thickness of (λ / 4-15 nm)_xI
n_1-xP_yAs_1-y(X = 0.5, y = 1) layer, C
Doped p-Al_zGa_1-zAs (z = 1) selective oxidation
Layer (thickness 30 nm), thickness (2λ / 4-15 nm)
C-doped p-Al_xGa_1-xAs layer (x = 0.9)
GaAs layer (one period) having a thickness of λ / 4, and C-doped
P-Al_xGa_{1 -X}As layer (x = 0.9) and pA
l_xGa_1-xAs (x = 0) layer in each medium
Period alternately stacked with a thickness of 1/4 of the oscillation wavelength
Structure (22 periods)
Reflector (Al_0.9Ga_0.1As / GaAs upper part
Reflecting mirror). Note that in this example as well, FIG.
Although illustration is omitted because it is complicated, semiconductor components
The structure of the cloth Bragg reflector has a low refraction as shown in Fig. 2.
Index layer (low refractive index layer) and high refractive index layer (high refractive index layer)
In the meantime, Al whose refractive index takes a value between small and large_zGa_1-z
Heterospike relaxation consisting of As (0 ≦ y <z <x ≦ 1)
An opposing layer is provided. And the topmost p-Al
_xGa_1-xThe As (x = 0) layer connects the electrode and the contact.
Contact layer (p-contact layer)
They also have a role.

Here, the In composition x of the quantum well active layer is 37
%, And the N (nitrogen) composition was 0.5%. Also the quantum well activity
The thickness of the conductive layer was 7 nm. In addition, this surface-emitting type semiconductor laser
The laser was grown by MOCVD. Semiconductor laser
The raw material for each layer is TMA (trimethylaluminum).
), TMG (trimethylgallium), TMI (g)
Limethylindium), AsH₃(Arsine), PH₃
(Phosphine), and DMHy
Methylhydrazine) was used. DMHy decomposes at low temperature
Therefore, it is suitable for low-temperature growth below 600 ° C.
A highly strained quantum well layer that requires low temperature growth
Preferred in the case. The carrier gas is H₂Was used.
In this example, a GaInNAs layer (quantum well active layer) is used.
Grew at 540 ° C. MOCVD has a high degree of supersaturation
Suitable for crystal growth of materials containing N and other V-groups at the same time
You. Also, high vacuum is not required unlike the MBE method,
Control the supply flow rate and supply time of
Is also excellent. Furthermore, in this example, a mesa
Part is p-Ga_xIn_1-xP_yAs _1-y(X = 0.
5, y = 1) p-Al until the layer is reached_zGa_1-zA
s (z = 1) is formed by exposing the side surface of the selective oxidation layer,
Al that appeared on the side_zGa_1-zAs (z = 1) layer is steamed
Oxidized from the side with air_xO_yForming a current narrowing layer
ing.

Finally, a mesa etch with polyimide (insulating film)
The part removed by polishing is embedded and flattened, and the upper reflector
Remove polyimide on top and emit light on p-contact layer
A p-side electrode is formed except for the portion, and n-side electrode is formed on the back surface of the GaAs substrate.
Side electrodes were formed. In this example, the selective oxidation layer
The lower part has Ga as part of the upper reflector._xIn _1-xP_yA
s_1-y(0 <x ≦ 1, 0 <y ≦ 1)
You. For example, in the case of wet etching,
If a chant is used, GaIn can be used for an AlGaAs system.
PAs based can be used as etch stop layer
Therefore, Ga_xIn_1-xP_yAs_1-y(0 <x ≦ 1,
0 <y ≦ 1) Insertion of the layer allows selective oxidation.
The height of the mesa etching can be strictly controlled. others
Therefore, uniformity and reproducibility can be improved, and cost can be reduced.
In addition, the surface emitting semiconductor laser (element) of this example is reduced to one dimension.
Or two-dimensional integration, controllability during device fabrication
Improves the characteristics of each element in the array.
The effect is that the uniformity and reproducibility of
You. In this example, G serving as an etching stop layer is also used.
a_xIn_1-xP_yAs_{1 -Y}(0 <x ≦ 1, 0 <y ≦
1) The layer is provided on the upper reflector side, but is provided on the lower reflector side
May be. In this example, too,
In addition, the active region where carriers are injected and recombine (this embodiment)
Then, the upper and lower spacer layers and the multiple quantum well active layer
Including the Al in the active region.
Low refractive index layers of lower and upper reflectors without using materials
The layer closest to the active layer of_xIn_1-xP_yAs
_1-yNon-radiative recombination prevention (0 <x ≦ 1, 0 <y ≦ 1)
And layers. That is, in this example, the
The interface between the mirror and the active region should not contain Al
Therefore, at the time of carrier injection, crystal defects caused by Al
Can reduce non-radiative recombination due to entrapment
You. It should be noted that the interface between the reflector and the active region does not contain Al.
It is preferable to apply the configuration to the upper and lower reflectors as in this example.
It is effective even if applied to only one of the reflectors
There is. In this example, both the upper and lower reflecting mirrors have a semiconductor distribution block.
Rag reflector was used, but one reflector was
And the other reflector as a dielectric reflector
good. Further, also in this example, between the GaAs substrate and the active layer.
The same idea as in the example of FIG. 1 was applied to the lower reflector of
Therefore, a crystal caused by Al, which is a problem when growing the active layer,
Negative effects due to crawling of defects into active layer are suppressed
As a result, the active layer can be grown with high quality crystals. What
In addition, such a non-radiative recombination preventing layer is provided in FIG. 1 and FIG.
In either configuration, a semiconductor distributed Bragg reflector
The thickness of the oscillating wave in the medium.
The thickness is set to １ ／ of the length λ (thickness of λ / 4). Ah
Alternatively, a plurality of layers may be provided.

Although the example in which the non-radiative recombination preventing layer is provided in a part of the semiconductor Bragg reflector has been described above, the non-radiative recombination preventing layer may be provided in the resonator. For example,
The resonator section is composed of an active layer composed of a GaInNAs quantum well layer and a GaAs barrier layer, and GaAs is a first barrier layer.
A structure in which a non-radiative recombination preventing layer made of nPAs, GaAsP, and GaInP is used as the second barrier layer is exemplified. The thickness of the resonator section can be one wavelength. Since the band gap of the non-radiative recombination prevention layer is larger than that of the GaAs first barrier layer, the active region into which carriers are injected substantially extends to the GaAs barrier layer. Also, the remaining Al raw material,
In the case where a step of removing an Al reactant, an Al compound, or Al is provided, the step may be provided in the middle of the non-radiative recombination preventing layer, or a GaAs layer may be provided between the non-radiative recombination preventing layer and the layer containing Al. And can be performed in the middle of the layer. As is clear from the above description, a surface-emitting type semiconductor laser having high luminous efficiency and sufficient reliability for practical use was obtained with such a configuration. Also, not all of the low refractive index layers of the semiconductor distributed Bragg reflector, but at least the portion closest to the active region is Ga _x In containing no Al.
_{1-x Py} As _1-y (0 <x ≦ 1, 0 <y ≦ 1) is used as the non-radiative recombination preventing layer, so that the above-described effect can be obtained without particularly increasing the number of stacked reflectors. I was able to.

In addition, even in such a configuration, since the polyimide can be easily embedded, the wiring (p-side electrode in this example) is hardly disconnected, and a device having high reliability can be obtained. The oscillation wavelength of the surface emitting semiconductor laser manufactured in this manner was about 1.3 μm. In this example, a layer composed mainly of Ga, In, N, and As was used as the active layer (GaInNAs active layer), so that a long-wavelength surface emitting semiconductor laser could be formed on a GaAs substrate. Also, the current was narrowed by selective oxidation of the selectively oxidized layer mainly composed of Al and As, so that the threshold current was low. According to the current narrowing structure using the current narrowing layer made of the Al oxide film in which the selective oxidation layer is selectively oxidized, the current spreading can be suppressed by forming the current narrowing layer close to the active layer,
Carriers can be efficiently confined in a minute region that does not come into contact with the atmosphere. Further, by oxidizing to form an Al oxide film, the refractive index is reduced, light can be efficiently confined in a minute region in which carriers are confined by the effect of a convex lens, the efficiency is extremely improved, and the threshold current can be reduced. . In addition, because the current narrowing structure can be easily formed,
Manufacturing costs can be reduced. As is clear from the above description, even in the configuration as shown in FIG. 10, as in the case of FIG.
A surface emitting semiconductor laser in the 1.3 μm band can be realized, and a low-power and low-cost device can be obtained. FIG.
The surface-emitting type semiconductor laser of 0 is similar to the MOC of FIG.
Although growth can be performed by the VD method, other growth methods such as the MBE method can also be used. In addition, D
Although MHy was used, activated nitrogen and other nitrogen compounds such as NH ₃ can also be used. Further, an example of a triple quantum well structure (TQW) is shown as a stacked structure of the active layer, but a structure (SQW, DQW, M
QW) can also be used. The structure of the laser may be another structure. In the surface-emitting type semiconductor laser shown in FIG. 10, the composition of the GaInNAs active layer is changed so that the 1.55 μm band, and further, the longer wavelength 1.7 μm.
An m-band surface emitting semiconductor laser is also possible. GaInN
Other III-V group elements such as Tl, Sb, and P may be contained in the As active layer. In addition, GaAsSb is used for the active layer.
Can realize a 1.3 μm band surface emitting semiconductor laser on a GaAs substrate.

In the present invention, the active layer is mainly composed of Ga, In, or As (GaInAs active layer), or the main element to which N is added is Ga, In, or As.
Although the description has been given using the layer composed of N and As (GaInNAs active layer), other than GaNAs, GaPN, GaN
PAs, GaInNP, GaNAsSb, GaInNA
sSb and the like can also be suitably used. Particularly in the case of an active layer containing nitrogen as in these examples, the non-radiative recombination preventing layer of the present invention is particularly effective. This will be described below. FIG.
1 is GaInNAs fabricated by our MOCVD equipment.
GaInNA composed of a quantum well layer and a GaAs barrier layer
5 shows a room temperature photoluminescence spectrum of an active layer having an s / GaAs double quantum well structure. FIG. 12 shows a sample structure. On a GaAs substrate 201, a lower cladding layer 202, an intermediate layer 203, an active layer 204 containing nitrogen,
An intermediate layer 203 and an upper cladding layer 205 are sequentially laminated. In FIG. 11, A is a sample in which a double quantum well structure is formed on an AlGaAs cladding layer with a GaAs intermediate layer interposed therebetween, and B is GaAs on a GaInP cladding layer.
This is a sample in which a double quantum well structure is continuously formed with an intermediate layer interposed therebetween. As shown in FIG. 11, the photoluminescence intensity of Sample A is lower than that of Sample B by less than half. Therefore, using one MOCVD apparatus, AlGa
Ga on a semiconductor layer containing Al as a constituent element such as As
When an active layer containing nitrogen such as InNAs is continuously formed, there is a problem that the emission intensity of the active layer is deteriorated. Therefore, the threshold current density of the GaInNAs-based laser formed on the AlGaAs clad layer is more than twice as high as that formed on the GaInP clad layer.

The elucidation of the cause was examined. FIG. 13 shows the nitrogen and oxygen concentrations when an element having a cladding layer of AlGaAs, an intermediate layer of GaAs, and an active layer of a GaInNAs / GaAs double quantum well structure was formed using a single epitaxial growth apparatus (MOCVD). FIG. 5 is a diagram showing a distribution in a depth direction. The measurement was performed by SIMS. Table 1 shows the measurement conditions.

[Table 1] In FIG. 13, two nitrogen peaks are observed in the active layer corresponding to the GaInNAs / GaAs double quantum well structure. Then, an oxygen peak is detected in the active layer. However, the oxygen concentration in the intermediate layer containing neither N nor Al is about one digit lower than the oxygen concentration in the active layer. On the other hand, the cladding layer is made of GaInP, the intermediate layer is made of GaAs, and the active layer is made of GaInNAs / GaAs2.
When the distribution of the oxygen concentration in the depth direction was measured for the element configured as the quantum well structure, the oxygen concentration in the active layer was at the background level. That is, when a semiconductor light emitting device having a semiconductor layer containing Al between a substrate and an active layer containing nitrogen is continuously grown by a single epitaxial growth apparatus using a nitrogen compound raw material and an organic metal Al raw material, Our experiments revealed that oxygen was incorporated into the active layer containing nitrogen. Oxygen incorporated in the active layer forms a non-radiative recombination level,
The luminous efficiency of the active layer is reduced. Oxygen incorporated in this active layer causes A between the substrate and the active layer containing nitrogen.
It has been newly found that this is a cause of lowering the luminous efficiency of a semiconductor light emitting element provided with a semiconductor layer containing l. The origin of this oxygen is considered to be a substance containing oxygen remaining in the apparatus or a substance containing oxygen contained as an impurity in the nitrogen compound raw material.

Next, the cause of the incorporation of oxygen was examined. FIG. 14 is a diagram illustrating the distribution of Al concentration in the depth direction of the same sample as in FIG. 13. The measurement was performed by SIMS. Table 2 shows the measurement conditions.

[Table 2] FIG. 14 shows that Al was detected in the active layer into which the Al material was not originally introduced. However, in the intermediate layer (GaAs layer) adjacent to the semiconductor layer containing Al (cladding layer), the Al concentration is about one digit lower than that of the active layer. This indicates that Al in the active layer is not diffused, replaced or mixed in from the semiconductor layer (cladding layer) containing Al. On the other hand, like GaInP, Al
When an active layer containing nitrogen was grown on a semiconductor layer containing no, Al was not detected in the active layer. Therefore,
The Al detected in the active layer is the Al source remaining in the growth chamber or in the gas supply line, or an Al reactant, or an Al compound, or Al reacts with the nitrogen compound source or impurities (such as moisture) in the nitrogen compound source. It is bonded and taken into the active layer. That is, when a semiconductor light emitting device having a semiconductor layer containing Al between a substrate and an active layer containing nitrogen is continuously crystal-grown by a single epitaxial growth apparatus using a nitrogen compound raw material and an organic metal Al raw material. It was newly found that Al was naturally taken into the active layer containing nitrogen. Compared with the depth distribution of nitrogen and oxygen concentrations in the same device shown in FIG. 14, the two oxygen peak profiles in the double quantum well active layer do not correspond to the nitrogen concentration peak profiles. Corresponding to the Al concentration profile. From this, the oxygen impurities in the GaInNAs well layer are:
It became clear that rather than being taken in with the nitrogen source, they were taken in together with Al taken in the well layer. That is, when the Al raw material or Al reactant remaining in the growth chamber or the Al compound or Al comes into contact with the nitrogen compound raw material, the moisture contained in the Al and the nitrogen compound raw material or the water remaining in the gas line or the reaction chamber. Al and oxygen are taken into the active layer by bonding with a substance containing oxygen such as. Our experiments have clarified for the first time that oxygen taken into the active layer has reduced the luminous efficiency of the active layer. Therefore, in order to improve this, at least the nitrogen source material or the Al source material or the Al reactant remaining at the place where the impurities contained in the nitrogen compound source contact the growth chamber.
It was found that it was necessary to provide a step for removing the l-compound or Al.

If this step is provided between the growth of the semiconductor layer containing Al and the start of the growth of the active layer containing nitrogen, when a nitrogen compound raw material is supplied to the growth chamber to grow the active layer containing nitrogen, Residual Al raw material or Al reactant,
Alternatively, an Al compound or Al reacts with a nitrogen compound raw material or an impurity contained in the nitrogen compound raw material and a substance containing oxygen remaining in the device to reduce the concentration of Al and oxygen impurities taken into the active layer. We were able to. Further, it is preferable to remove the non-radiative recombination preventing layer after the growth thereof, since the adverse effect on non-radiative recombination in the active layer can be suppressed when carriers are injected into the active layer by current injection. For example, by reducing the Al concentration in the active layer containing nitrogen to 1 × 10 ¹⁹ cm ⁻³ or less,
Room temperature continuous oscillation became possible. Further, by reducing the Al concentration in the nitrogen-containing active layer to 2 × 10 ¹⁸ cm ⁻³ or less, light emission characteristics equivalent to those formed on a semiconductor layer containing no Al were obtained. Al source or Al reactant or Al remaining in the growth chamber where the nitrogen compound source or impurities contained in the nitrogen compound source touch.
The step of removing the compound or Al includes, for example, providing a step of purging with a carrier gas. Here, the time of the purge step is set after the growth of the Al-containing semiconductor layer is completed and the supply of the Al raw material to the growth chamber is stopped.
It refers to an interval until a nitrogen compound raw material is supplied to a growth chamber to start growth of a semiconductor layer containing nitrogen. As a method of the purging, there is a method of interrupting the growth in an intermediate layer containing neither Al nor nitrogen and purging with a carrier gas. In the case where the growth is interrupted and the purge is performed, the place where the growth is interrupted can be provided between the growth of the Al-containing semiconductor layer and the middle of the non-radiative recombination preventing layer.

FIG. 15 shows an example of a sectional structural view of a semiconductor light emitting device for explaining that a step of purging with a carrier gas in the present invention is provided. 15, a first semiconductor layer 202 containing Al as a constituent element, a first lower intermediate layer 601, a second lower intermediate layer 602, an active layer 204 containing nitrogen, and an upper intermediate layer 20 are formed on a substrate 201.
Third, the second semiconductor layer 205 is sequentially stacked. For crystal growth, an epitaxial growth apparatus using an organic metal Al raw material and an organic nitrogen raw material is used. A growth interruption step is provided between after the growth of the first lower intermediate layer and the start of the growth of the second lower intermediate layer. During the growth interruption, the Al source material, the Al reactant, or the Al compound, or the Al remaining in the growth chamber where the nitrogen compound source material or the impurities contained in the nitrogen compound source material touch is purged with hydrogen as a carrier gas. Has been removed. FIG.
6 is a first lower intermediate layer 601 and a second lower intermediate layer 60
2 shows a measurement result of the distribution of the Al concentration in the depth direction in a semiconductor light emitting device in which the growth was interrupted between 2 and the purge time was set to 60 minutes. As shown in FIG. 16, the Al concentration in the active layer is 3 ×
It could be reduced to 10 ¹⁷ cm ⁻³ or less. This value is about the same as the Al concentration in the intermediate layer. FIG.
FIG. 7 shows the result of measuring the distribution of the nitrogen and oxygen concentrations in the depth direction for the same device. As shown in FIG. 17, the oxygen concentration in the active layer was reduced to a background level of 1 × 10 ¹⁷ cm ⁻³ . The reason why a peak appears in the oxygen concentration in the lower intermediate layer is that oxygen segregates at the growth interruption interface. Therefore, in the case of purging after interrupting the growth, it is preferable that the place where the growth is interrupted be provided after the growth of the Al-containing semiconductor layer until the end of the growth of the non-radiative recombination preventing layer. The non-radiative recombination prevention layer can increase the bandgap energy compared to the quantum well active layer and the barrier layer. This is because adverse effects due to the above can be suppressed. When an active layer containing nitrogen is used as described above, providing a non-radiative recombination preventing layer is particularly effective.

In this semiconductor light emitting device, the growth is interrupted between the first lower intermediate layer and the second lower intermediate layer, and the purge time is reduced to 6 hours.
By providing for 0 minutes, Al and O in the active layer containing nitrogen are removed.
, Etc. could be reduced. This allows
The luminous efficiency of the active layer containing nitrogen could be improved.
In the step of purging the growth chamber with a carrier gas, by purging the susceptor while heating it,
The Al raw materials and reaction products adsorbed on the susceptor or around the susceptor can be degassed and removed efficiently. However, when the substrates are heated simultaneously, it is necessary to keep supplying a group V source gas such as AsH ₃ or PH ₃ to the growth chamber even during the interruption of the growth, in order to prevent the semiconductor layer on the outermost surface from being thermally decomposed. is there. Further, when purging the growth chamber with a carrier gas, the substrate can be transferred from the growth chamber to another chamber. By transporting the substrate from the growth chamber to another chamber, there is no need to supply a group V source gas such as AsH ₃ or PH ₃ to the growth chamber when purging while heating the susceptor. Therefore, the thermal decomposition of the reaction product containing Al deposited around the susceptor or the susceptor can be further promoted. Thereby, the Al concentration in the growth chamber can be efficiently reduced. Also,
There is a method of purging while growing the intermediate layer. Since the non-radiative recombination preventing layer is provided between the AlGaAs-based reflecting mirror containing Al and the active layer containing nitrogen,
Since the distance between the layer containing Al and the active layer containing nitrogen becomes longer, there is an advantage that the purge time can be lengthened even when purging is performed while growing. In this case, it is better to slow down the growth rate and lengthen the time. In addition, Al containing Al
There is also a method in which a GaAs-based reflecting mirror and an active layer containing nitrogen are formed by different apparatuses. Even in this case, if the regrowth interface is provided below the non-radiative recombination preventing layer, the concentration of impurities such as Al and O in the active layer containing nitrogen can be reduced.

In the case where the semiconductor layer containing Al is provided between the substrate and the active layer containing nitrogen, a semiconductor layer containing Al is provided between the substrate and the active layer containing nitrogen. No report has been made on the decrease in luminous efficiency of the semiconductor light emitting device. On the other hand, in the MOCVD method, it has been reported that the luminous efficiency of a GaInNAs active layer formed on a semiconductor layer containing Al decreases. Electron.Let
t., 2000, 36 (21), pp1776-1777, the same MOC
Even when an intermediate layer made of GaAs is provided on the AlGaAs cladding layer in the VD growth chamber, GaInNAs is continuously formed.
It has been reported that when a quantum well layer is grown, the photoluminescence intensity is significantly deteriorated. In the above report, in order to improve the photoluminescence intensity, A
An lGaAs cladding layer and a GaInNAs active layer are grown in different MOCVD growth chambers. Therefore, MOCV
In the case of a crystal growth method using an organic metal Al raw material and a nitrogen compound raw material as in the method D, this is a problem that occurs at least. In the MBE method, crystal growth is performed under ultra-low pressure (in a high vacuum). On the other hand, in the MOCVD method, the pressure in the reaction chamber is generally higher than several tens of Torr to about atmospheric pressure. It is considered that the supplied raw material and carrier gas are overwhelmingly short and come into contact with and react with others in a gas line, a reaction chamber, or the like. Therefore, like the MOCVD method,
When the pressure in the reaction chamber or gas line is high,
After the growth of the semiconductor layer containing nitrogen, before the growth of the active layer containing nitrogen, and more preferably, after the end of the growth of the non-radiative recombination preventing layer, contained in the nitrogen compound raw material or the nitrogen compound raw material in the growth chamber. Al raw material, Al reactant, or Al compound, or Al remaining at the place where the impurities touch
Is effective in preventing oxygen from being taken into the active layer containing nitrogen. For example, A
There is also a method in which a gas line or a growth chamber is evacuated after growing a semiconductor layer containing 1 and before growing an active layer containing nitrogen. In this case, the effect is high if heating is performed.

There is also a method of removing the semiconductor layer containing Al by flowing an etching gas after growing the semiconductor layer before growing the active layer containing nitrogen. An example of a gas that can react with and remove an Al-based residue is an organic-based compound gas. As described above, when a DMHy gas, which is one of the organic compound gases, is supplied using a DMHy cylinder during the growth of the active layer containing nitrogen, it is apparent that the gas reacts with the Al-based residue. Therefore, after growing a semiconductor layer containing Al,
When organic compound gas is supplied using an organic compound gas cylinder before the growth of the active layer containing nitrogen, Al-based residue remaining on the reaction chamber side wall, the heating zone, the jig holding the substrate, and the like. Can be removed by reacting with oxygen, so that the incorporation of oxygen into the active layer can be suppressed. Furthermore, it is preferable to use the same gas as the nitrogen material of the active layer containing nitrogen, since it is not necessary to add a special gas line. This step may be performed with the growth interrupted.
A layer containing nitrogen, such as an NAs or GaInNP layer, may be formed by crystal growth as a dummy layer separately from the active layer. It is preferable to perform the Al removal step by crystal growth as compared with the case where the growth is interrupted, because there is no time loss. Note that Ga is used for the active layer.
In the case of using InAs, it has conventionally been considered that the wavelength limit is 1.1 μm or less, but it is possible to grow a GaInAs quantum well active layer having a high strain with a high strain by growing at a low temperature of 600 ° C. or less. , The wavelength can reach up to 1.2 μm. As described above, a semiconductor laser having a wavelength of 1.1 μm to 1.7 μm does not have a material suitable for a conventional semiconductor laser. Wavelength of 1.1 μm to 1.7 μm, which has conventionally been difficult to achieve stable oscillation
In the long wavelength region of the band, a high-performance surface emitting laser can be realized, and application to an optical communication system has become possible.

FIG. 18 shows an example in which such a long wavelength band surface emitting semiconductor laser device is formed as a large number of chips on an n-GaAs wafer 40 having a (100) plane orientation, and a laser device chip. In the laser element chip shown here, 1 to n laser elements 41 are formed, and the number n and the arrangement method are determined according to the application. FIG. 19 shows that the laser oscillation wavelength is 1.1.
This is an example of an optical transmitting and receiving system using a long-wavelength surface emitting semiconductor laser in a μm band to a 1.7 μm band. In this example, a laser element light emitting unit 50, which is a light emitting light source, is installed at point A. The emitted optical signal is optically coupled to the optical fiber 51 and transmitted in the transmission direction indicated by the thick arrow 52 in the figure. Then, the optical fiber is optically coupled to a light detector 53 of a light receiving element such as a photodiode which is a light receiving unit installed at a point B which is a terminal end of the optical fiber, and functions as an optical transmitting and receiving system. In this example, the installation location A of the light emitting light source and the installation location B of the light receiving unit are optical fibers 51.
This is an example of connecting by a straight line. FIG. 20 is also an example of an optical transmitting and receiving system using a long-wavelength surface emitting semiconductor laser having a laser oscillation wavelength of 1.1 μm to 1.7 μm. In this example, the laser element light emitting section 55 is an optical fiber F
1, and the emitted light is transmitted in the transmission direction 56 indicated by the thick arrow in the figure. After that, 9
The optical fiber F2 is bent in the direction of 0 °, enters the optical fiber F2, and is optically coupled to an optical detector 58 of a light receiving element such as a photodiode at the end of the optical fiber F2, and functions as an optical transmission / reception system. Although this example is for explaining the features of the optical transmitting and receiving system of the present invention, and shows only one laser element light emitting portion, the features of the long wavelength band surface emitting semiconductor laser suitably applied to the present invention. Taking advantage of
A plurality of laser elements may be formed on one chip, and an optical fiber optically coupled to the chip and a plurality of light receiving elements may be used as a multi-laser array type system capable of large-capacity optical transmission and reception.

FIG. 21 shows an example in which such an optical transmission / reception system of the present invention is arranged in a premises, and is an example in which it is arranged in a wall of a building. Here, a long-wavelength surface emitting semiconductor laser 60 having a laser oscillation wavelength of 1.1 μm band to 1.7 μm band, which is a light emission light source, is arranged at a point A in a building,
A photodiode 61 as a light receiving unit is installed at a point, and a reflection member 62 for changing the direction of the transmission path is provided between the points A and B. In this figure, a plan view of a room is shown, and the figure shows an optical transmission / reception system in a large scale for explanation, and the scale of the room or wall and the optical transmission / reception system do not match. Further, although not shown, each of the optical transmission / reception units at both the points A and B has other connection devices or connectors. These may be inside the wall, from which terminals and the like may be drawn into the room.

FIG. 22 shows a plan view of a room in an example in which a conventional optical transmission / reception system is arranged in a premises. In this case, the laser element 63 and the photodiode 64 are connected in a straight line by an optical fiber 65, and the optical fiber is arranged across the inside of the room. Since such optical fibers are arranged across the room, they are arranged on the floor, under the floor or on the ceiling of the room. FIG. 23 also shows a plan view of a room in an example in which a conventional optical transmission / reception system is arranged in a premises. Also in this case, the laser element and the photodiode are connected by an optical fiber, but the optical fiber is arranged in a curved line by utilizing the flexibility of the optical fiber. However, even if the flexibility of the optical fiber is utilized, only the direction of the transmission path can be changed with a large curvature, and the optical fiber is also arranged across the room, so that it is arranged on the floor, under the floor or on the ceiling of the room. You. In the conventional arrangement method shown in FIGS. 22 and 23, the optical fibers are arranged so as to cross the room, so that the optical fibers on the floor, under the floor or in the ceiling of the room are arranged very complicatedly and randomly, and a plurality of these are arranged. Then, there is a problem that they become entangled with each other and become entangled with each other, which makes maintenance and the like difficult. In particular, when it is placed on the floor, it is very dangerous that pedestrians can catch their feet. However, in the present invention as shown in FIG. 21, the direction of the transmission line can be bent by 90 ° by the reflection member. Since the optical fiber transmission lines can be arranged in an orderly manner along, etc., even if the optical fiber transmission lines are arranged in a visible place rather than inside a wall, they are also beautifully arranged. Also, even if multiple pieces are arranged,
There is no entanglement, and subsequent maintenance and the like can be easily performed. In constructing such an in-house optical transmission / reception system, a reflection member for changing the direction of the transmission line is provided, so that the transmission line can be efficiently arranged according to the shape of the building, and an unnecessary transmission line is provided. Is exposed to the eyes, the ceiling of the building,
The transmission path does not unnecessarily occupy the area under the floor or inside the wall, so that the building can be effectively designed and the degree of freedom in aesthetic design increases. When the direction of the transmission path is bent by the reflection member, it is not necessarily 90
There is no need to bend to °. However, when a building is usually designed / constructed, its pillars, walls, floors, and ceilings are designed / constructed based on straight lines and planes intersecting the straight lines at 90 ° unless there is a special design requirement. Considering that, the optical fiber transmission line is a pillar,
When placing along a wall, floor, ceiling, etc., the direction
It is more preferable to change the angle by 0 ° in terms of efficiency and aesthetic appearance. When the direction of the transmission line is changed by 90 ° in this manner, when constructing such an optical transmission / reception system, unnecessary transmission lines are exposed to the eyes or the ceiling, under the floor or on the wall of the building. The transmission line does not occupy an area more than necessary inside, and the building design can be effectively performed, and the degree of freedom to the aesthetic design increases.

[0041]

As described above, according to the first aspect of the present invention, by devising a semiconductor distributed Bragg reflector,
The operating voltage, oscillation threshold current, and the like can be reduced, stable oscillation can be performed with little heat generation of the laser element, and a low-cost and practical in-building (premises) optical transmission / reception system can be realized. Further, when constructing such an optical premise transmission / reception system, a reflection member for changing the direction of the transmission line is provided, so that the transmission line can be efficiently arranged according to the shape of the building, and unnecessary The transmission line is not exposed to the eyes, and the transmission line does not occupy more area than necessary in the ceiling, under the floor, or inside the wall. The degree of freedom has increased. According to the second aspect of the present invention, a surface-emitting type semiconductor laser device chip provided with a non-radiative recombination preventing layer enables stable oscillation, thereby realizing a practical optical transmission / reception system using this as a light emitting light source. . Furthermore, in constructing such an optical transmission / reception system within a premises, a reflection member for changing the direction of the transmission line is provided, so that the transmission line can be efficiently arranged according to the shape of the building, which is unnecessary. The transmission line is not exposed to the eyes, and the transmission line does not occupy more area than necessary in the ceiling, under the floor, or inside the wall. The degree of freedom has increased. According to the third aspect, the reflection member for changing the direction of the transmission line changes the direction of the transmission line by 90 °, so that the transmission line can be efficiently arranged according to the shape of the building.

[Brief description of the drawings]

FIG. 1 is a sectional view of an element part of a long-wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a configuration of a semiconductor distributed Bragg reflector of a long wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 3 is a diagram showing an example in which the composition gradient of the hetero-spike buffer layer of the semiconductor distributed Bragg reflector applied to the present invention is larger near the GaAs layer than the AlAs layer.

FIG. 4 is a diagram showing an example in which the Al composition of the hetero-spike buffer layer is changed linearly.

FIG. 5 is a diagram showing a result of estimating a differential sheet resistance of the hetero-spike buffer layer of FIG. 3;

FIG. 6 is a band diagram showing a thermal equilibrium state of a DBR heterointerface of a semiconductor distributed Bragg reflector made of AlAs / GaAs.

FIG. 7 is a band diagram of the hetero-spike buffer layer of FIG. 3 in a thermal equilibrium state.

FIG. 8: AlAs / GaAs (p = 1E18 cm ⁻³ )
It is a figure which shows the resistivity of 4 pairs.

FIG. 9 is a graph showing the rate of change of the reflectance of an AlAs / GaAs semiconductor distributed Bragg reflector.

FIG. 10 is a sectional view of an element portion of another configuration of a long-wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 11 shows GaInNAs / according to an embodiment of the present invention.
FIG. 3 is a room-temperature photoluminescence spectrum diagram of an active layer having a GaAs double quantum well structure.

FIG. 12 is a structural diagram of a sample.

FIG. 13 is a diagram showing a depth direction distribution of nitrogen and oxygen concentrations.

FIG. 14 is a diagram showing the distribution of the Al concentration in the depth direction.

FIG. 15 is an explanatory structural view in the case where growth is interrupted by carrier gas purge.

FIG. 16 is a diagram showing the distribution of the Al concentration in the depth direction in a case where a growth interruption step is provided and purged with hydrogen.

FIG. 17 is a diagram showing a depth direction distribution of nitrogen and oxygen concentrations when a growth interruption step is provided and purged with hydrogen.

FIG. 18 is a plan view showing a wafer substrate and a laser element chip on which a long wavelength band surface emitting semiconductor laser element according to one embodiment of the present invention is formed.

FIG. 19 is a diagram illustrating an example of an optical transmitting and receiving system in which a light emitting light source and a light receiving unit are linearly connected by a transmission line.

FIG. 20 is a diagram showing an example of an optical transmitting and receiving system using a long wavelength band surface emitting semiconductor laser device of the present invention as a light source.

FIG. 21 is a plan view of a room in an example in which the optical transmission / reception system of the present invention is arranged in a premises.

FIG. 22 is a plan view of a room in an example where a conventional optical transmission / reception system is arranged in a premises.

FIG. 23 is a plan view of a room in another example where a conventional optical transmission / reception system is arranged in a premises.

[Explanation of symbols]

1 n-side electrode, 2 n-GaAs substrate, 3 lower distributed Bragg reflector, 4 GaAs spacer layer, 5 upper distributed Bragg reflector, 6 p-contact layer,
12 TQW active layer, 13 GaAs barrier layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Teruyuki Furuta 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Kazuya Miyagaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Ken Kanai 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Atsushi Watada 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Shunichi Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Yukie Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Invention Satoru Sugawara 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Shuichi Hikichi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Inside Ricoh (72) Inventor Shinji Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Naoto Shakuya 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. 72) Inventor Takashi Takahashi 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. 2H037 AA01 BA02 BA11 CA38 DA03 DA04 5F073 AA07 AA08 AA51 AA65 AA74 AB17 BA02 CA07 CA17 DA05 DA27 EA23

Claims (3)

[Claims] An oscillation wavelength is 1.1 μm to 1.7 μm, and a main element of an active layer for generating light is Ga, In, or Ga.
A surface-emitting type semiconductor laser comprising a layer made of N and As or a layer made of Ga, In and As, and having a resonator structure including reflectors provided above and below the active layer to obtain a laser beam. An element chip, wherein the reflection mirror has a reflection wavelength of 1.1 μm or more, and the refractive index of a material layer constituting the reflection mirror periodically changes to a value different from that of the reflection mirror, and reflects incident light by light wave interference. In addition to the distributed Bragg reflector, the material layer having a small refractive index is Al _x Ga
_1-x As and (0 <x ≦ 1) and the material layer of the refractive index is large is _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1) and then, and the refractive index of the small and large material the refractive index between layers has a value between the small and large _{Al z Ga 1-z as (} 0 ≦ y <z <x
≦ 1) from 20 nm to 50
A surface-emitting type semiconductor laser device chip as a reflecting mirror provided with a thickness of nm is used as a light emitting light source, and an optical fiber transmission line for transmitting an optical signal to the light emitting light source is optically coupled. In an optical transmitting and receiving system provided with a light receiving unit optically coupled to the side of the road opposite to the light emitting light source, the optical transmitting and receiving system,
A premises optical transmission / reception system for performing communication inside a building, wherein the light emitting light source is installed at a first point in the building, and the light receiving unit is installed at a second point in the building, and An optical transmission / reception system, wherein a reflection member for changing the direction of the transmission path is provided between the second points. 2. An oscillation wavelength of 1.1 μm to 1.7 μm, and a main element of an active layer for generating light is Ga, In,
A surface-emitting type semiconductor laser comprising a layer made of N and As or a layer made of Ga, In and As, and having a resonator structure including reflectors provided above and below the active layer to obtain a laser beam. An element chip, wherein the reflection mirror has a reflection wavelength of 1.1 μm or more, and the refractive index of a material layer constituting the reflection mirror periodically changes to a value different from that of the reflection mirror, and reflects incident light by light wave interference. In addition to the distributed Bragg reflector, the material layer having a small refractive index is Al _x Ga
_1-x and As (0 <x ≦ 1) , the material layer of the refractive index is large is a reflective mirror which is a _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), wherein said active layer the main composition between reflector _{Ga x in 1-x P y} As 1-y (0 <x ≦ 1,0 <
y ≦ 1) A surface emitting semiconductor laser device chip provided with a non-radiative recombination preventing layer composed of a layer is used as a light emitting light source, and an optical fiber transmission line for transmitting an optical signal to the light emitting light source is optically coupled. In addition, in the optical transmission / reception system provided with a light receiving unit optically coupled to the transmission path on the side opposite to the light emission light source, the optical transmission / reception system is a premises optical transmission / reception system for performing communication inside a building. Installing the light emitting light source at a first point in the building and the light receiving unit at a second point in the building;
An optical transmission / reception system, wherein a reflection member for changing the direction of the transmission path is provided between the first point and the second point. 3. The reflection member has a direction of the transmission path of 9
The optical transmission / reception system according to claim 1, wherein the optical transmission / reception system performs 0 ° conversion.