JPH01302885A - Integrated optical semiconductor element - Google Patents

Abstract

PURPOSE:To obtain an element which can decide a positional relationship between a laser and a detector with a high accuracy of about 1mum and can detect it stably by using an ordinary lithographic technique by a method wherein a semiconductor laser and a specific detector are formed on an identical substrate. CONSTITUTION:A semiconductor laser and a detector are formed on an identical substrate 8. Since the detector has at least two p-n junctions, it detects a position of a photodetecting spot in a direction perpendicular to the p-n junctions; since it has at least two surface electrodes, it can detect a position of a photodetecting spot in a direction transverse to the p-n junctions. for example, a p-type GaAlAs, GaAlAs active layer, an n-type GaAlAs, GaAlAs active layer and a P-type GaAlAs layer are grown continuously on a semiinsulating GaAs substrate 8; the upper part other than a detector part is removed. In addition, a laser part and the detector part are separated electrically by executing an etching operation; after that, a groove is formed in the central part of the detector part; a photodetecting part composed of four independent active layers is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an integrated optical semiconductor element used for optical pickup of an optical disk device.

Conventional technology In recent years, compact discs and video discs.

2. Description of the Related Art So-called optical disk devices, such as optical memories, which process information using light, are occupying a large position in the information processing field. Optical pickups are used for inputting and outputting information in these optical pickup devices. An example of a conventional optical pickup is shown in FIG. Light emitted from the semiconductor laser 1 is focused onto the disk 2 by an optical system such as a lens. The reflected light from the disk is also focused on the detector 3 by an optical system and converted into an electrical signal. A hologram optical element (Holo) is attached to this optical pickup.
Graphic 0ptical Element:
HOE) reduces the number of parts,
Hologram optical pickups are smaller and lighter.

FIG. 4 shows an example of a conventional hologram optical pickup. A hologram optical element (HOE) 4, a collimating lens 5, a detector chip 6, and a semiconductor laser chip 7 are housed in the same path cage. The reflected light from the disk is diffracted by the HOE, and the first-order diffracted light enters the detector chip and is used as a signal.

Compared to the conventional optical pickup shown in FIG. 1, there are fewer parts and the optical path can be simplified.

Problems to be Solved by the Invention However, conventional hologram optical pickups have the following problems. That is, the positional accuracy when fixing the detector chip and the semiconductor laser chip in the package is very strict, requiring an accuracy of several μm, resulting in a very complicated assembly process and poor yield.

Means for Solving the Problems In order to solve the above problems, the optical semiconductor device of the present invention includes:
A semiconductor laser and a detector are formed on the same substrate,
The detector has at least two pn junctions and two surface electrodes, and is characterized in that it can detect the position of the light receiving spot.

Effect: By the means described above, the positions of the semiconductor laser and the photodetector can be controlled with sufficiently high precision using phosphorography technology.

Example Embodiments of the present invention will be described using the drawings.

FIGS. 2a and 2b show the manufacturing process of an embodiment of the present invention.

p-type Ga, -y1e am S on semi-insulating G & M S substrate 8
9. Ga, , A/xAs active layer A10. n-type Ga, ,
Ae, MuS11, Ga, -. M”XAS active layer B 12
, p-type Ga, -yA (yAs13) are successively grown (Fig. 2a). This wafer is etched,
The upper active layer B other than a part of the detector is removed (second
Figure b). This wafer is further etched,
After electrically separating the laser part and a part of the detector, a groove is also formed in the central part of the detector to form a light receiving part consisting of four independent active layers. An integrated optical semiconductor device is obtained.

Next, the operation of this embodiment will be explained. FIG. 6 is a circuit diagram of the embodiment shown in FIG. A semi-insulating substrate is used, and the laser and detector are completely insulated, so their signals do not mix with each other. A laser emits light by passing a current between a p-side electrode and an n-side electrode. On the other hand, the detector has a configuration that can function similarly to a 4-split photodetector, and focus errors (FiC) and tracking errors (Tic) can be detected, for example, as follows.

FE=(PD1+PD4)-(PD2+PD3)TE=
(PDl + PD2') - (PD3 + PD4) In the above example, a 1 μm
The positional relationship between the laser and the detector can be determined with a high degree of accuracy, making stable detection possible.

Effect of the invention The integrated optical semiconductor device of the present invention is a semiconductor laser.

By forming the detectors on the same substrate, their mutual positional relationship can be controlled with high precision using phosphorography technology, which has great practical value.

[Brief explanation of the drawing]

FIG. 1 is a completed diagram of an embodiment of the present invention, FIGS. 2 a to b are manufacturing process diagrams of an embodiment of the present invention, FIG. 3 is a diagram showing an example of a conventional optical pickup, and FIG. 4 is a diagram of a conventional optical pickup. FIG. 6, which shows a hologram optical pickup, is a circuit diagram of an embodiment. 8... Semi-insulating GaAs substrate, 9...
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Claims (1)

[Claims] A semiconductor laser and a detector are formed on the same substrate,
The detector has at least two pn junctions to detect the position of the light receiving spot in the direction perpendicular to the pn junction, and has at least two surface electrodes to detect the position of the light receiving spot in the direction parallel to the pn junction. An integrated optical semiconductor device characterized by being capable of detecting.