JPH0228388A - Semiconductor laser element - Google Patents

Abstract

PURPOSE:To obtain a semiconductor laser element having high output with transverse mode oscillation by arranging the constitution such that it has refractive index difference between a mesa stripe part equivalent to a wave guide path and a region other than it, and further setting properly the thicknesses and composition ratios of a light guide layer and other each layer. CONSTITUTION:A light guide layer 12 is provided between an active layer 13 and the first clad layer 11, and a mesa stripe part consisting of each layer positioned above the active layer 13 is formed, and light absorbing layers 16 are provided on both sides of it, whereby it is constructed such that it has equivalent refractive index difference between the stripe part and the part other than the stripe part. Hereby, the necessity of forming a V groove vanishes, and it becomes possible to manufacture it easily using a vapor growth method, and basic transverse mode oscillation can be realized by controlling the refractive index difference in the transverse direction by the etching depth in formation of the stripe part in manufacturing process. Also, by properly setting the thickness of the light guide layer 12 and the composition ratio of each layer by this construction, high output operation can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an index-guided semiconductor laser device having a light guide layer.

[Conventional technology]

A refractive index guided semiconductor laser device having a rib waveguide, which is advantageous for controlling the oscillation mode, is provided with an optical guide layer in order to achieve high output. This is shown in the schematic cross-sectional view of Figure 4. In FIG. 4, this semiconductor laser device is manufactured by forming an n-GaAs 2 as a current blocking layer on a P-GaAs substrate 1, etching the surface to form a groove, and then proceeding to form a P-AJ)( Ga 1
-XAS first cladding layer 3°P -AJ3 y Ga
+ -y As light guide layer 4. P-person Az (3a 1
-2As active layer 5 * n-A-e) (Gal-xAs
A second cladding layer 6, an n-GaAs layer, and a first layer 7 are sequentially laminated by liquid phase growth. 8.9 are the upper and lower electrodes, respectively.

Under what conditions does fundamental mode oscillation occur in a semiconductor laser device with the structure shown in Figure 4? By causing the laser light to seep into the optical guide layer 4, the optical density in the active layer 3 is reduced by instantaneous optical damage (COD).
The device structure is designed to obtain high output at a level below the level of 120 mW or higher, and the thickness of the optical power layer 4 and the composition of each layer have been studied. is known to be obtained.

[Problem to be solved by the invention]

4. Forming a waveguide by sanding as shown in FIG. 4 is only possible through liquid phase growth. This is because in liquid phase growth, when the thickness increases to a certain extent, the narrow surface becomes flat, and the layers above the active layer 5 are formed flat. On the other hand, when the vapor phase growth method is used, each layer including the active layer 5 is in a curved state because the crystals of the constituent layers are grown along with the V-groove.

Therefore, it is not possible to obtain a sufficient difference in light transversely.

However, when manufacturing the device, it is preferable to use a vapor phase growth method, which is easy to form a thin film and is advantageous in obtaining a large-area device.

The present invention has been made in view of the above-mentioned points, and its purpose is to provide a material that can be easily manufactured by vapor phase growth, has a sufficient difference in refractive index in the lateral direction, and has a light guide layer. An object of the present invention is to provide a semiconductor laser device having a tangled structure.

[Means for solving problems]

The semiconductor laser device of the present invention includes a first cladding layer, an active layer, a second cladding layer, and a second cladding layer, which are stacked on one principal surface of a semiconductor substrate by vapor phase growth. The active layer of the clad polishing and cap layer and the first. A light guide layer of the same conductivity type as the cladding layer is provided between one of the second cladding layers, and both sides of the mesa stripe part parallel to the laser beam traveling direction are formed by each layer located above the active layer. It has a structure in which the surface has an original absorption layer having a conductivity type opposite to that of the mesa stripe portion.

[Effect]

In the semiconductor laser device of the present invention, the optical guide layer 12 is activated l-
13 and the first cladding layer 11 (FIG. 1), or between the active layer 13 and the second cladding layer 14a (FIG. 3), the light guide layer 12a is provided between the active layer 13 and the second cladding layer 14a (FIG. 3), and from each layer located above the active layer 13. The structure is such that a mesa striated portion is formed, and light absorption doves 16 are provided on both sides of the mesa striated portion to provide an isometric refractive index difference between the mesa striated portion s and the region other than the striped portion, as shown in Fig. 4. There is no need to worry about forming a thin layer, and it is now possible to easily manufacture T using the vapor phase growth method. Mode oscillation can be realized. Further, in this structure, high output operation can be obtained by appropriately determining the thickness of the optical guide layer and the composition ratio of each layer.

〔Example〕

The present invention will be explained below based on examples.

FIG. 1 is a schematic sectional view of the semiconductor laser device of the present invention seen from the front. FIG. 1 shows, for example, an n-An) (Ga s-x spring S first cladding layer 1 on an n-GaAs substrate lO.
1゜A#yGa t-yAs original Ga light guide layer a P-
k13zOa 1-2As activity IInt i'-A-e
xGa, -xhs second cladding layer 14 and P-GaA
A mesa stripe is formed on the second cladding layer 14 and the cap layer 15, and an n-GaAs light absorption layer 16 is formed on both sides of the mesa stripe parallel to the direction in which the laser beam travels. This is a structure embedded with . 17 and 18 are electrodes.

FIGS. 2(a) to 2(c) show the order of the main steps to describe the manufacturing method of this semiconductor laser device.
Parts common to those in the figure are indicated by the same reference numerals. The semiconductor laser device of the present invention having the structure shown in FIG.
Chemical Vapor Deposition
) can be used.

MOCVD is more advantageous than liquid phase growth in terms of mass productivity and film thickness control when forming a large-area epitaxial film.

First, for example, on an n-GaAs substrate 10 with a carrier concentration lX10 m and a thickness 150 μm, n-AJo, s*Ga (Lllll A
s Pa 1 cladding layer U.

Carrier concentration ixtomt thickness l pm n - A-1
3o, gv Ga (L7S As original guide layer 12.l
Ya1J711E[I
As active layer 13. P-A-13ast Ga 0969 with carrier concentration 1XIQ bx and thickness l pm
A s second cladding layer 14N! and carrier concentration 3×10
One layer 15 of P-Gak@Kya having a length of 1 m and a thickness of 0.5 pm is grown in a vapor phase in this order. Next is the cap skin 15
After depositing an 8i02 film to a thickness of 2 pm on the second side of the
The state in which the film is removed and the 8i01 film 19 remains is shown in Figure 2 (]. Next, the removed portion other than the 5i02 film 19 is coated to a depth of about 1.3 μm from the optical surface, and the first layer 15 and the second layer 15 are removed. Mesa etching is performed to the middle of the cladding layer 14 and the second cladding layer 14 is removed.

Form a mesa stripe section consisting of
Figure (b)]. Furthermore, due to vapor phase epitaxial growth again, the refractive index is lower than that of the mesa stripe part, and the carrier concentration is 1x.
A 10 1 n-QaAs light absorption layer 16 is grown to a thickness of 1.3 Pm on the surface other than the mesa stripe, the uZnSi02 film 19 is removed, and finally the /Au P@A
By covering the front and back surfaces of the uGe 17 and /Au n-side electrodes 18 by vapor deposition or the like, a semiconductor laser device having the same structure as that shown in FIG. 1 can be obtained [FIG. 2(C)].

The thus obtained semiconductor laser device of the present invention oscillates continuously at room temperature with a threshold current of 30 to 40 mA at an oscillation wavelength of 830 nm, and has a maximum optical output of 15 in fundamental transverse mode oscillation.
It showed 0 mW.

Further, in the device structure of the present invention, the original guide layer 12 is the active layer 13.
and Kl cladding layer 11. Since it is sufficient to provide it between the second cladding layer 14 and either one of the cladding layers, the structure as shown in FIG. 3 can be achieved. FIG. 3 is a schematic cross-sectional view similar to FIG. 1, and common parts are denoted by the same reference numerals. However, the difference from FIG. 13 and the second cladding layer 14a, that is, on the active layer 13, and the mesa stripe portion is the optical guide layer 12a.

It is formed by the second cladding layer 14a and the cap skin 15.

The manufacturing method for the device structure shown in FIG. 3 is basically the same as that shown in FIG. 1. First, each layer is grown on the substrate 10 in the order shown in FIG. Mesae to the middle of the light guide layer 12a.

After forming a mesa stripe portion by etching, a light absorption layer 16 is embedded. This structure has the same characteristics as the structure in which the light guide layer 12 is provided below the active layer 13 as shown in FIG.
The light seeps into the 6 side, causing loss to the horizontal higher-order mode oscillation, and the effect of suppressing the generation of higher-order modes is significant.

〔Effect of the invention〕

A refractive waveguide-decreasing semiconductor laser device having an optical guide layer and a lip waveguide has conventionally been manufactured by a liquid phase growth method that forms a VJ, but it is easy to control the thickness of the thin film and to obtain a large-area device. As described in the embodiment, in the present invention, as a structure without a V-groove that enables the application of the advantageous vapor phase growth method, a light guide layer is disposed either above or below the active layer, and is located above the active layer. A mesa stripe section consisting of each layer is formed, and a light absorption layer with a conductivity type opposite to that of the mesa stripe section is provided on both sides of the mesa stripe section, so that there is a difference in refractive index between the mesa stripe section corresponding to the waveguide and the other regions. By creating a structure in which the optical guide layer and the other layers have a structure having the following properties and by appropriately determining the thickness and composition ratio of the optical guide layer and other layers, it was possible to obtain a semiconductor laser device having high output power in fundamental transverse mode oscillation.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the semiconductor laser device of the present invention, and FIG.
Figure 3 is a schematic cross-sectional view of the semiconductor laser device of the present invention in which the arrangement of the light guide layer is different from that in Figure 1, and Figure 4 is a diagram of the conventional refractive index guide having a light guide layer. FIG. 2 is a schematic cross-sectional view of a wave-type semiconductor laser device. 1. IO...substrate, 3.11... first clad skin,
4.12゜12a... Light guide layer, 5.13... Active layer, 6.14.14a... Second cladding layer, 7.1
5... Cap layer, 8.9.17°18... Electrode,
16...Light absorption layer, 19...8i02 film. Number Z diagram

Claims (1)

[Claims] 1) A first cladding layer of one conductivity type, an active layer of opposite conductivity type, a second cladding layer of opposite conductivity type, and a cap layer of one conductivity type, which are laminated on one main surface of a semiconductor substrate of one conductivity type by a vapor phase growth method. A mesa having a light guide layer of the same conductivity type as the cladding layer between the active layer and either the first or second cladding layer, and formed by each layer located above the active layer. A semiconductor laser device characterized in that a light absorption layer having a conductivity type opposite to that of the mesa stripe portion is provided on both side surfaces of the stripe portion parallel to the direction in which the laser light travels.