JPS58135690A - Vertical oscillation type semiconductor laser - Google Patents

Abstract

PURPOSE:To form a wavelength selecting vertical type light resonator and thus obtain a vertical oscillation type semiconductor laser available to an integration and a high output with stable oscillation wavelength, by growing two kinds of thin film with different dielectric constants alternately above and under an active layer. CONSTITUTION:A GaAlAs-GaAs multilayer film for which a molecular beam epitaxy (MBE) technique is used is decided as the material, and the active layer 3 is sandwiched between interference type reflection layers 2 and 4, and forms a light cavity vertically to an N type GaAs substrate 5. By keeping the upper electrode 1 at the potential of approx. 2V in opposition to the lower electrode 2, electrons and hole current are supplied into the active layer 3 and then re- coupled resulting in a light emission. Among emission spectrums, only those of wavelength 0.8mum are confined in the upper and lower reflection layers 2 and 4 into the state of laser oscillation. A part of the laser light is vertically irradiated from a window provided at the center of the upper electrode 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vertical oscillation type semiconductor laser that enables higher integration and higher output of semiconductor lasers.

The first IIc optical cavity structure proposed for semiconductor lasers was Fabry-Bello's, which uses a laborator surface, but this structure was difficult to integrate and also lacked wavelength selectivity in the laser beam. It has drawbacks such as instability of the single oscillation wavelength. To compensate for these drawbacks, IIM has been proposed in which a periodic W structure is formed in the leading waveguide by etching or the like, and Bragg reflection is performed. However, since the wavelength of light in a semiconductor laser is shortened by the refractive index of the medium, there is a problem that the processing volume is large and the reflection efficiency of elements actually created using photoresist technology is not large. there were. In addition, all conventional semiconductor lasers have a structure in which the laser beam is emitted from between the ends, so the area of the emission end is small, and the output energy of the laser beam is small.
Even when integrated, there are problems such as the inability to obtain a two-dimensional array structure.

The present invention was made to solve these problems, and by growing two types of thin films with different dielectric constants alternately above and below the active layer, vertical optical resonance with wavelength selectivity is achieved. The present invention will be described below. FIG. 1 is a schematic diagram of the configuration of an embodiment according to the present invention. The vertical oscillation type laser beam according to the present invention, MBE (molecular beam
It is made of a GaAl B-Ga 8-beam multilayer structure using the taxy (taxy) technology, and includes an upper m electrode 1, an upper interference type reflective layer 2, an active layer 8, a lower interference type reflective layer 4, and an n'' Ga
It is composed of an As substrate 5 and a lower electrode 6. As shown in FIG. 7, the active layer 8 is sandwiched between upper and lower interference type reflective layers 2.4 to form an optical cavity perpendicular to the n''GaAr; substrate 5. As shown in FIG.

11 Layer 2 shows a band diagram of the vertical oscillation laser shown in the first rail. The upper and lower interference reflective films 2 are a 60 nm GaAg thin film 2xs41 and a 66 layer mt Ga@, respectively, corresponding to the h cavity wavelength of the laser light (Qt voice m). It has a laminated structure of about several dozen layers, with 8 layers of 2m and 4m. In addition, each active layer 8 has a thickness of 3 ml! P-GaAs layer 81 and n-Ga
It is composed of an As layer 33. By changing the upper electrode 1 to the lower electrode 2 and keeping it at a potential of about 2 hiro, electron and hole currents are supplied to the central active layer through the PIIi and n-type upper and lower reflective layers, respectively, and are recombined. Of the zero emission spectrum emitted by the laser, only the wavelength at the lowest wavelength is confined by the upper and lower reflective layers 8.4, resulting in a laser oscillation state. A part of the laser light is emitted vertically from the window provided in the center of the upper electrode 1. In Fig. 2, the upper interference type reflective layer S does not exhibit conductivity even if it is non-doped. −.

In addition, in FIG. 2, the active layer 8 is omitted, and the Q&A 8 layers j! in the upper and lower reflective layers are omitted. It is also possible to utilize IS 41 as a light emitting region.

The t/83 diagram shows the number of times the interference type thin film layer is overlapped and the QIII of the optical resonator whose ends are sandwiched between these reflective layers.
The reflection loss at K is shown. These reflective layers consist of a G&Aa layer with a thickness of 40 m and a unii Ga@, yml (
1. It is composed of SM B layer, and the number of superposition is 1.
The thickness of the reflective film increases by (1/3μl).The horizontal broken line in the figure shows the loss ratio λ of the 7 Abry-Pérot type resonator using reflection from the boundary between GJLA B and air. As is clear from the intersection of ◎Assuming that the thickness of the active layer is ≦7, and the average gain during forward current conduction is ≦oocm''''1, the gain is Since the loss curve intersects at about the 60th layer position, this vertical oscillation laser has 60 layers, that is, about J:j reflection layers above and below the active layer of ≦7 layers. From the formation k, it can be seen that oscillation is possible.No.
The dependence of optical resonance loss on oscillation wavelength is shown. It can be seen that the thin reflective layer has high diffraction efficiency and wavelength selectivity compared to the planar Bragg diffraction waveguide using optical lithograph 7 technology. The IIS diagram shows Ga using the vertical oscillation lid laser.
8 This is an example in which a laser matrix was created on a semi-insulating substrate.
Laser main body L8, 4 consisting of 1 reflective layer 8, 4 and active layer 8
, n'' conductive layer 7, element isolation insulating film 8, and Ga 11g
It is composed of a semi-insulating substrate 9. Upper electrodes l and n
By choosing a combination with the "lli layer", the laser body 2 at the place where the upper electrode 1 and the n" conductive layer 7 intersect.
．． 8.4 can be written in the forward direction. Therefore, n0
While applying a negative voltage to any number of conductive layers 7, the upper electrode 1
By sequentially holding the laser array at ground potential, it is possible to sequentially sweep the laser array vertically while changing the light emitting pattern of the laser array in the horizontal direction. This example is an example in which a txt matrix is formed, but by using an appropriate driving device, for example,
Can be used as a character generator. In addition, high-speed line printers or 2! By using a &×2j6 laser array, it is possible to construct an image pattern generator or a three-dimensional hologram generator. To enumerate the technical advantages of the vertical oscillation type semiconductor laser having the structure of the present invention, since the emission direction of the I laser is perpendicular to the substrate, the area of the I -1 emitted light can be increased.
It is possible to create a laser with a high output of several 1 or more.

Since the light intensity at the I-2 active layer and the output end face can be lowered, the life can be extended.

I Since the trout 11 is not used as a reflective surface, 1-1
Easy to integrate. In particular, the two-dimensional laser matrix is 1
It can be created for the first time using this structure.

1-2 Good production yield as there is no damage to the end face due to g# opening -0 1-84! Since residual elastic strain associated with IIK does not occur, a longer life can be expected.

l Since a coherent thin film is used as the reflective layer of the optical resonator, a reflector with an h wavelength period, which could not be manufactured using conventional photoresist technology, can be manufactured with high precision. Therefore, the reflection efficiency and wavelength selectivity of the reflective layer are high, and high oscillation wavelength stability can be obtained with a low threshold current.

MBK (MO1ecul&r Beam Epita
xy) technology, it is relatively easy to manufacture the multilayer structure necessary for the above reflective layer using I-Ms or l-V group compound semiconductors with good reproducibility. Compared to the 7-applied bellow lid or the Brafgri 7-rector Ij & cow conductor laser, which have not been put into practical use in the past, the #i of this invention has improved output, lifespan, oscillation wavelength stability, ease of integration, and manufacturing time. It is excellent in all aspects such as yield, etc., and is suitable for all fields in which semiconductors will enter the future.
For example, optical communications, video discs, laser printers,
Image pattern generators, power lasers, etc. are expected to replace conventional structures.

[Brief explanation of the drawing]

1st fj! J is a schematic diagram of the configuration of the vertical oscillation laser of the present invention,
The band diagram of the 2nd WAti vertical oscillation type laser, Figure 3 is a diagram explaining the number of superimpositions of the interference type thin film and the resonator loss, Figure 1
The figure is a diagram explaining the dependence of the resonator loss on the oscillation wavelength of an interference thin film, the lj figure (←) is a plan view of a laser matrix using a vertical oscillation lid laser according to the present invention, and (k) is a cross-sectional view of the same laser matrix. be. In the figure, l is the upper electrode, 2 is the upper interference type reflective layer, 3 is the active layer, 4 is the lower interference reflective layer, 5hn" cam S substrate, 6 is the lower electrode, 7 is the n" GaAa conductive layer, and 8 is the Insulating film for element isolation, 9#1 Gans semi-insulating substrate. Procedural amendment (voluntary) February 11, 1989 411 Commissioner of the Japan Patent Office Kazuo Chikusugi Tono 1 case display 1982 patent mlll/7g753 2g & name of Ming - Directly installed 1itaitei conductor laser 3 Correction, Relationship with the case of a patent applicant Chiyo, Tokyo [11-ku Jokusanseki 1-1” 3-1 t;1] 4
Ishizaka, Director of Institute of Technology
Makoto-4 Designated Agent 1-1-4X, Baizono, Sakuramura, Niiharu-gun, Ibaraki Prefecture” (1) In the specification, “Reioi I” in the third line of page 183 and in the IIS line is corrected to “nGaAs J.” ( 2) Same, page 3, line '1113 tD "p-GaA
s layer 81 and n-GaA3 J pGaAs layer 8
1 and nGaAs J. (3) Similarly, r p GaAs 2 l "p"GaAs Zx and p'"GaAugs28" in line S of page d.
and p GaAlAs 2 s J and correct 0(4)
``n''GaAs 41 and n''G on page 9, line 7.1.
aAlAg43” to “n GaAs 41 and n GaA
Correct it to lA34 s J. (5) Same, “boocx-”” on the 7th line of the INS page was changed to “6
00S′″1”. (6) Same, tH page 9, j+ line A, r n”GaA
Correct s J to [n GaAs J. (7) Figures A2 and 3 of the drawings are corrected as shown in the attached sheet. Procedural Amendment (Directive) ' Showa SR J No. 1 Lambda Reference 11 Commissioner of the Japan Patent Office Kazuo Wakasugi Tono 1 Indication of Case 1962 Patent Application 1i/7174t, i No. 2 Name of Invention Vertical emitting mWl semiconductor laser Kasumigaseki, Chiyoda-ku, Tokyo 1-3-1-114 Industrial Technology Director Ishi
Makoto Saka -4 Designated Agent, 1-1-4, Baizono, Sakuramura, Niiharu-gun, Ibaraki Prefecture 6 Subject of amendment' Contents of amendment The column ()) of the procedural amendment submitted dated February 1999, Showa Sg, was corrected as follows. ◇ "()) Correct Figures 1 and 1113 of the drawings as shown in the attached sheet." to "()) Correct Figures 1, 2, and 3 of the drawings as shown in the attached sheet." I am corrected.

Claims (1)

[Claims] A vertical oscillation semiconductor laser characterized in that a wavelength-selective vertical optical resonator is formed by providing a multilayer structure of conductive dielectric thin films above and below an active layer of the semiconductor laser.