JPS6212180A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To use a P-N junction between a current blocking layer and a clad layer as a photodetector by forming an ohmic electrode to the blocking layer while being separated from an electrode for injecting currents to a laser. CONSTITUTION:An electrode 9 is connected to positive electricity and an electrode 8 to negative electricity, and a bias is applied. Currents flow through an active layer 3 just under a window section for a blocking layer 5, and a laser oscillates in the active layer 3. Beams in the active layer 3 in the lower section of the blocking layer 5 are absorbed to the blocking layer 5 at that time, thus oscillating the laser at a stable fundamental lateral mode in a section just under the window section for the blocking layer 5. One part of photons in the active layer 3 is absorbed by the blocking layer 5, thus leading out the signal of the absorbed photons between electrodes 8 and 10. That is, a reverse bias is applied to a P-N junction between the blocking layer 5 and a P-type clad layer 4 through a resistor, thus operating the P-N junction as a photodetector, then making the P-N junction to fill the same role as a photodetector which has been fitted to the rear of a laser diode.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a semiconductor laser device that can be used as a light source for optical communications or a light source for compact discs.

Conventional Technology Conventionally, when using a semiconductor laser, in order to obtain a constant optical output, a so-called Mutomltic Power (PC) is used, which detects the light emitted from the rear of the laser with a light receiving element and feeds the signal back to the laser drive circuit. Con
trol) action is taken.

For this purpose, a light receiving element must be bonded behind the laser tip and placed so as to detect the laser beam.

Problems to be Solved by the Invention As mentioned above, when arranging the laser and the light receiving element, if the laser end face is coated with a high reflectance, the light output extracted to the rear will be reduced, and the detection current of the light receiving element will be reduced. It becomes difficult for people to operate their PC. Furthermore, it becomes impossible to increase the output of the laser by coating the back surface with high reflectance. Furthermore, when the light receiving element is placed behind the laser, there is a problem in that when the reflected light from the surface of the light receiving element returns to the laser, the longitudinal mode of the oscillated light becomes unstable.

In view of the above-mentioned problems, the present invention provides a semiconductor laser device that can perform a PC operation without disposing a light receiving element behind the laser.

Means for Solving the Problems In order to solve the above problems, a semiconductor laser device of the present invention includes a double heterostructure including an active layer formed on a -conductivity type semiconductor substrate, and a double heterostructure including an active layer. A layer having the same conductivity type as the substrate and having a forbidden band equal to or less than the forbidden band of the active layer and having a striped window is formed thereon, and an electrode for injecting current through the striped window, and The structure includes an ohmic electrode provided on a layer provided with shaped windows.

Operation With this configuration, light generated within the active layer can be detected by applying a reverse bias to the pn junction between the striped layer and the cladding layer above the active layer.

Examples Examples of the present invention will be described below with reference to the drawings.

The driving factor shows a semiconductor laser device in one embodiment of the present invention. 1 is n-type G & M S board, 2 is n-sent l
X Ga1-1A s cladding layer, 3 is non-doped A%
Ga, yAs active layer, 4 is p Saint l) ('cal-X
'AS layer This is a cladding layer and functions to confine carriers and light in the active layer 3. Reference numeral 5 indicates an n-type GaAs current blocking layer that limits the region of current injected into the active layer, 6 indicates a p-type nx'Ga1z' S cladding layer similar to the cladding layer 4, and 7 indicates a p-type GaAs layer for forming an ohmic electrode. 8 is an ohmic electrode provided on the substrate side, 9 is an ohmic electrode for injecting current into the active layer 3, and 1o is a blocking layer 5
This is an ohmic electrode for applying a bias to.

The thickness of the cladding layer 2 is 2 μm, and the thickness of the active layer 3 is 0.1 μm.
μm, the thickness of cladding layer 4 is 0.3μm, cladding layer 6
The thickness of the blocking layer 6 is 2 μm, and the thickness of the blocking layer 6 is 1.6 μm.
The window width is 6 μm at the top and bottom, respectively, 3
It is μm. The thickness of the p-type 0&S layer 7 is 0.5 μm.

The operation of the semiconductor laser configured as described above will be explained.

First, the electrode 9 is connected to the positive terminal, and the electrode 8 is connected to the negative terminal. Since the light in the active layer 3 below the layer 5 is absorbed by the blocking layer 5, oscillation occurs in a stable fundamental transverse mode directly under the window portion of the blocking layer 6.

Since some of the photons in the active layer 3 are absorbed by the blocking layer 5, a signal of the absorbed photons can be extracted between the electrodes 8 and 10.

That is, pn between the block layer 6 and the p-type cladding layer 40
By applying a reverse bias through a resistor to the junction,
The pn junction can be operated as a photodetector,
It serves the same purpose as a conventional photodetector attached to the rear of a laser diode.

Furthermore, by increasing the reflectance to 100% by coating the rear surface of the laser cavity, a high-output laser capable of APC operation can be obtained.

In the examples, GaAs-Ga 1AS material was used, but the material is not limited to this material (Inp-I
Any m-v, m-■ group semiconductor, including nGaAsP, and their mixed crystals may be used as long as they have the above-mentioned functions. Further, the electrode portion of the block layer 5 may be provided on one side of the laser oscillation section, and the shape of the electrode may be arbitrarily determined. An insulating film can also be used between the electrodes to separate the electrodes 9 and 10.

Effects of the Invention As described above, the present invention provides an ohmic electrode in the current blocking layer separate from the electrode for current injection into the laser, thereby making it possible to use the pn junction between the blocking layer and the cladding layer as a photodetector. It is possible, and its practical effects are similar to that of a dog.

[Brief explanation of the drawing]

Turning is a perspective view of a semiconductor laser device in an embodiment of the present invention. 1-----・-n-GaAs substrate, 2"・"・n A
JzGal-xA! i, 3...Non-dope person 1
7G&+yAs active layer, 4...P-11
1' Ga, ! 'person s, 6i---・---
n-GaAs, 6----P-Alz'Ga
+z'muS17...P-GaAS, 8.1
0...n-type ohmic electrode, 9...p
type ohmic electrode.

Claims (1)

[Claims] A double heterostructure including an active layer is formed on a semiconductor substrate of one conductivity type, and the substrate is provided with a striped window having a forbidden band width equal to or less than the forbidden band width of the active layer on the double heterostructure. A semiconductor laser device characterized in that a layer of the same conductivity type is formed, and has an electrode for injecting current from the striped window, and an ohmic electrode provided on the layer having the striped window. .