JPH01272177A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To make it possible to form easily a plurality of pieces of semiconductor laser elements, which have high output and are large in the difference in oscillation wave, on the same semiconductor substrate by a method wherein the layers for actuating one piece of the element among a plurality of pieces of the laminated semiconductor laser elements are formed of an epitaxial growth layer having a double heterostructure different from that of an epitaxially grown layer, of which the layers for actuating the other elements are formed. CONSTITUTION:Multilayer crystal layers (a p-type Ga1-yAlyAs clad layer 4, a Ga1-xAlxAs active layer 5 and an n-type Ga1-yAlyAs clad layer 6) having a double heterostructure for actuating a first laser element 31 and multilayer crystal layers (a p-type Ga1-sAlsAs clad layer 10, a Ga1-zAlzAs active layer 11 and an n-type Ga1-sAlsAs clad layer 12) having a double heterostructure for actuating a second laser element 32 are respectively formed of each of epitaxially grown layers, whose double heterostructure are different from each other, in such a way that the layers 4, 5 and 6 and the layers 10, 11 and 12 are respectively formed right over a striped groove 3 and a striped groove 9. Accordingly, as the Al ratios (x) and (y) of mixed crystal of the layer 5 to the clad layers 4 and 6 and the Al ratios (s) and (t) of mixed crystal of the layer 11 to the clad layers 10 and 12 can be respectively set separately and the thicknesses of the layers 5 and 11 can be respectively set separately and uniformly, a laser beam, whose oscillation wavelengths are different from each other, are obtained from a laser oscillation part and a reduction in the thicknesses of the active layers indispensable to an increase in output can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a semiconductor laser in which a plurality of semiconductor laser elements having different oscillation wavelengths are integrated on the same semiconductor substrate.

(Prior Art) As a device in which a plurality of semiconductor laser elements having different oscillation wavelengths are integrated on the same semiconductor substrate, for example, JP-A-59-16
The one shown in FIG. 3 described in Japanese Patent No. 5487 is known.

This is formed as follows. That is, p-type GaAs
After growing an n-GaAs current blocking layer 42 on the substrate 41 by liquid phase epitaxial growth, stripe grooves 43 and 44 having a width of 11t*Vs (V process>w2) are etched until the current blocking layer 42 is removed to form a current path. form. A P-Ga1-vAlyAs cladding layer 45, a Ga, -1AQzAs active layer 46 (0<
process<y<1), an n-Gaz-vA4yAs cladding layer 47 and an n-GaAs cap layer 48 are sequentially laminated, and a p-side electrode 49 is further formed on the substrate 41. An n-side electrode 50 is formed on the cap layer 48. Next, in order to divide the multilayer crystal for laser operation into units of 43.44 stripe grooves, the n-side electrode 50 is
Separation grooves 51 are carved from the surface parallel to the stripe grooves 43 and 44, and etched until the depth reaches the current blocking layer 42.

As described above, the multilayer crystal active layers 46 stacked directly above the stripe grooves 43 and 44 with different widths are respectively curved and flattened, and the active layers 46 are set as epitaxial growth layers with different growth rates in accordance with the groove widths. It is possible to obtain an oscillation operating section with different oscillation wavelengths corresponding to the growth rate of the epitaxial growth layer.

(Problem to be Solved by the Invention) In a semiconductor laser that uses the difference in the width of the stripe grooves to form active layer regions with different growth rates and obtain different oscillation wavelengths, the active layer in the region where the width of the stripe grooves is large is Since it is curved, it is insufficient to make the active layer thin and obtain high output, and the transverse mode tends to become unstable as the output changes.

Also, the difference in the oscillation wavelength of each semiconductor laser element is 5 to 40+a
It is extremely difficult to easily obtain a plurality of semiconductor laser elements having a small wavelength of approximately m and a large difference in oscillation wavelength with little variation.

The present invention eliminates these drawbacks, and provides a method for optical communications and optical information processing, in which multiple semiconductor laser elements with high output and a large oscillation wave difference can be easily formed on the same semiconductor substrate. The purpose is to provide semiconductor lasers with different oscillation wavelengths.

[Structure of the invention]

(Means for Solving the Problems) The semiconductor laser of the present invention is a semiconductor laser in which a plurality of independently operable semiconductor laser elements are integrated on the same semiconductor substrate, in which at least one semiconductor laser element has a double heterostructure. The semiconductor laser device is characterized in that the junction is formed using an epitaxial growth layer different from the double heterojunction of other semiconductor laser devices.

(Function) By separately forming double heterojunction epitaxial growth layers of a plurality of semiconductor laser elements, a plurality of semiconductor laser elements can be independently driven to increase the composition ratio of the ternary or quaternary mixed crystal semiconductor. Can be formed on the same semiconductor substrate. Furthermore, since the active layer can be easily made thin, a high-output semiconductor laser can be formed.

(Embodiment) FIG. 1 shows a perspective view of a semiconductor laser according to an embodiment of the present invention.

In the semiconductor laser 30, a first semiconductor laser element 31 and a second semiconductor laser element 32 are integrally formed on the same semiconductor substrate 1. The cladding layer 4, active layer 5, and cladding layer 6 forming the double heterojunction of the first semiconductor laser element 31 and the second semiconductor laser element 32
The cladding layer 10, active layer 11, and cladding layer 12 that constitute the double heterojunction are formed by different epitaxial growth methods.

Hereinafter, the manufacturing process of this semiconductor laser 30 will be explained with reference to FIG.

First, a recess 20 is formed on the surface of a p-type GaAs substrate by etching (FIG. 2(a)).
After the current blocking layer 2 is grown by liquid phase epitaxial growth, the recess 2 is
0, a rectangular stripe groove 3 is formed by etching until the depth reaches the p-type GaAs substrate 1 (FIG. 1(b)).The current blocking layer 2 is removed and this stripe groove 3 is formed by etching until the depth reaches the p-type GaAs substrate 1. Current carrying rad layer 4 of element 31,
Ga, -xAjl, Ag active layer 5, n-Ga1-yA
ffiyAs cladding layer 6 (0< x < y <
1), sequentially stacking n-GaAs ohmic M7 (
(c)), this results in double heterojunction multilayer crystal layers 4, 5, 6 for operation of the first laser element with oscillation wavelength λ1.
6 Next, in order to form the second laser element 32, the multilayer bonding layers 4, 5, 6 of the first double heterojunction are formed between the recesses 20 until the depth reaches at least the current blocking part 2.
Then, the ohmic layer 7 is removed by etching (FIG. 4(d)).

On the substrate in which the double heterojunction portion of the first laser element 31 remains in a convex shape, the n-GaAs current blocking layer 8 is laminated again by the liquid phase epitaxial growth method. Thereafter, stripe grooves 9 are formed by etching in the same manner as the stripe grooves 3 until the depth reaches at least the substrate 1 (FIG. 1(e)).
This becomes the second current path.

Again, liquid phase epitaxial growth method, p-Ga1-Bi
gAs cladding layer 10, Ga1-tAj5As active layer 1
1. n-Gn-Ga1-gA1 cladding layer (0<t
< s < 1 )12. The n-GaAs ohmic layers 13 are sequentially laminated (FIG. 2(f)), thereby forming a double heterojunction multilayer crystal layer to, 11.12 for operation of the second laser element with an oscillation wave number λ2.

Next, the double heterojunction multilayer crystal layer 10, 11, 12 and the ohmic layer 13, which are laminated on the first laser element 31 and are used to operate at least the second laser element 32, are removed by etching. Allow current to flow through the laser ((g) in the same figure).

Again, by the liquid phase epitaxial growth method, the first laser element 31 and the second laser element 32 are formed into the recesses 21 and 32, respectively.
An n-GaAs ohmic layer 14 is laminated and flattened on the substrate formed on the convex portion 22.Next, the back surface of the substrate 1 is polished to a thickness that can be cleaved, and then the p-side layer is formed by vapor deposition. In order to divide the multilayer crystal layer for laser operation so that the electrode 15 and the n-side electrode 16 can be formed as bases, separation grooves 17 and cleavage grooves 18 are formed from the surface of the n-side electrode 16 parallel to the stripe grooves 3 and 9. Engraved.

Etching is performed until the depth reaches the GaAs substrate 1 (FIG. 1(i)).

Next, active layers 5 and 1 are separated along the groove 18 and placed directly above the stripe grooves 3 and 9 shown in FIG.
A semiconductor laser of the present invention is obtained in which laser oscillation operating parts that can be driven independently in one region are formed.

According to the present invention, the double heterojunction multilayer crystal layers 4 and 5 for operating the first laser element 31 are placed directly above the stripe groove 3.
, 6. Double heterojunction multilayer crystal layer 10.11.12 for operating the second laser element 32 directly above the stripe groove 9
Thus, a double heterojunction is formed using different epitaxially grown layers. As a result, the active layer 5 and the cladding layers 4 and 6 of the double heterojunction for the operation of the first laser element are formed.
The AQ mixed crystal ratio s and t of the active layer 11 and cladding layer 10.12 of the double heterojunction for operating the second laser element can be set separately, and the active Since the thicknesses of the layers 5 and 11 can be set separately and flatly, laser output lights with different oscillation wavelengths can be obtained from the laser oscillation section, and the active layer can be made thinner, which is essential for achieving high optical output.

In the above embodiment, each multilayer crystal layer of the double heterojunction has one
Although a case has been described in which a laser operating section is formed individually, a plurality of independently operable lasers may be formed in the same double heterojunction multilayer crystal layer.

〔Effect of the invention〕

According to the present invention, a plurality of semiconductor laser elements that can operate independently and have different oscillation wavelengths and have high output and stable transverse modes can be easily integrated on the same semiconductor substrate. Furthermore, since the double-heterojunction multilayer crystal layer of each laser element is formed of different epitaxial growth layers, the oscillation wavelength can be easily set, and a semiconductor laser with a large difference in oscillation wavelength can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagonal diagram of a semiconductor laser showing an embodiment of the present invention;
FIG. 2 is a diagram showing the manufacturing process of the semiconductor laser of the present invention, and FIG. 3 is an oblique view of the conventional semiconductor laser. Agent Patent Attorney Nori Chika Yudo Kikuo Takehana

Claims (1)

[Claims] In a semiconductor laser in which a plurality of semiconductor laser elements that can operate independently are integrated on the same semiconductor substrate, the double heterojunction of at least one semiconductor laser element is an epitaxial growth layer that is different from the double heterojunction of other semiconductor laser elements. A semiconductor laser characterized in that it is formed from.