JPH0461635A - Semiconductor element for optical disk - Google Patents

Abstract

PURPOSE:To miniaturize the device, to make a moving part light in weight, and to execute an access at a high speed by hybridizing a semiconductor laser, a monitor photodetector and a signal detecting photodetector on a silicon substrate having a V-shaped groove. CONSTITUTION:A monitor photodetector 4, and a signal photodetector 5 are formed on a silicon substrate 1 having a V-shaped groove 2, a semiconductor laser 3 is fixed, and also, subjected to wiring on a silicon substrate 1, and an emitted light front is attached so as to become parallel to the V-shaped groove 2. Accordingly, an emitted light from the front is emitted without being obstructed by the silicon substrate 1, reflected by the slant face of the V-shaped groove 2 and advances in the direction vertical to the substrate 1 surface. Subsequently, an emitted light from the rear face of the semiconductor laser 3 is inputted to the monitor photodetector 4, and the light quantity of the semiconductor laser 3 is monitored. Also, the reflected light is detected by the signal photodetector 5. In such a way, the device is miniaturized, the moving part is made light in weight, and the access can be executed at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical semiconductor element used in an optical head for an optical disk.

[Conventional technology]

In recent years, optical disks, which are large-capacity and inexpensive memories, have begun to be put into practical use as rough-fail image memories for office automation. However, although optical disks are superior in storage capacity to conventional magnetic disks, their data transfer and access speeds are slow. Therefore, in order to achieve higher speeds of optical discs, efforts are being made to rotate optical discs at higher speeds and to miniaturize optical heads.

[Problem to be solved by the invention]

In order to miniaturize optical heads, optical integrated and separated types are being developed, but integrated optical heads have an optical head element that integrates a semiconductor laser, a lens, and a photodetector. Proposed. However, it is difficult to realize an efficient thin film lens, and practical application is still considered to be a technology in the future. In addition, a separate type optical head has a moving objective lens and an actuator, which correspond to the eyeballs of the optical head, and a fixed photodetection system. By doing so, the weight of the moving section is reduced, and the access time of the optical head is shortened. However, in order to irradiate a light beam from a fixed part to a moving part, precision of the moving part is required, but conventional optical heads also have problems with reliability, and miniaturization of the device is not necessarily achieved. do not have.

[Means to solve the problem]

The semiconductor element for an optical disk of the present invention is one in which a semiconductor laser is integrated on a substrate of a photodetector in a hybrid manner. A first light-receiving element that receives the rear emitted light of the semiconductor laser and a second light-receiving element that receives a plurality of external lights are formed on the silicon substrate so as to be parallel to each other. Ru.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention. In FIG. 1, a monitor light receiving element 4. is mounted on a silicon substrate 1 having a V-shaped groove 2. A signal light receiving element 5 is formed. The semiconductor laser 3 is fixed and wired on the silicon substrate 1 by, for example, solder fusion. Since the semiconductor laser 3 is mounted so that the front surface of the emitted light is parallel to the V-shaped groove 2, the light emitted from the front surface is not blocked by the silicon substrate 1 and is reflected on the slope of the V-shaped groove 2. and moves in a direction perpendicular to the substrate surface. The light emitted from the rear surface of the semiconductor laser 3 is input to the monitor light receiving element 4, and the light emitted from the rear surface of the semiconductor laser 3 is
The amount of light is monitored. Further, in the optical head, information signals and servo signals are read by detecting reflected light from the disk medium, and a signal light receiving element 5 for detecting this reflected light is formed on the silicon substrate 1. This signal light receiving element 5 is a light receiving element divided into a plurality of parts to receive both information signals and servo signals. Power is supplied to the semiconductor laser 3 and detection signals are output from each of the light receiving elements 4 and 5 through electrodes.

In order to form the V-shaped groove 2 in the silicon substrate 1, it is sufficient to select a 45° etching easy axis direction of the silicon substrate by reactive etching. It is also possible to perform micro mechanical processing. Each of the light receiving elements 4 and 5 may be formed as a silicon light receiving element by a normal diffusion process. Further, in the semiconductor laser 3, an electrode 6 is formed on the silicon substrate 1 at the mounting portion, and each element can be fixed using low melting point solder. The alignment between the semiconductor laser 3 and each light receiving element 4.5 can be performed with accuracy on the order of microns by the above-mentioned directions.

FIG. 2 is a diagram illustrating the principle of an optical head using an optical semiconductor element according to the present invention. In FIG. 2, the optical head includes an optical semiconductor element 10. The hologram element 12 and objective lens 11 are housed in the head cap 1.
3 is entirely supported by a support casing 15. The light emitted from the optical semiconductor element 10 is transmitted to the hologram element 1
2 and an objective lens 11, the light is focused onto a disk 16. The reflected light from the disk 16 passes through the objective lens 11 again, is diffracted by the hologram element 12, and returns to the optical semiconductor element 10. This diffracted light enters the signal light receiving element 5 shown in FIG. 1, and the information signal and servo signal contained in the disk reflected light are detected. The entire head cap 13 is moved in the direction of the disk (in the direction of arrow A) by an actuator 14 to perform focusing control.
Tracking control is performed by moving in a direction perpendicular to this (in the direction of arrow B).

FIG. 3 is a diagram illustrating the operating principle of an optical head using an optical semiconductor element according to the present invention. In FIG. 3, the emitted light from the semiconductor laser 3 passes through the hologram element 12 and the objective lens 11 and is focused on the disk 16, and this reflected light passes through the objective lens 11 again and enters the hologram element 12. The diffracted light from the hologram element 12 is transmitted to the signal light receiving element 5.
The amount of light is detected. Hologram element 12
For example, as shown in FIG. 3, it is divided into four parts: H, , H2H3, and H4. Further, the light receiving element 5 includes, for example, s, s2. SS,s,,S.

and S6, an element divided into six is used.

Then, when light enters the hologram element 12, the area H
The diffracted light from area H2 is transmitted to the receiving elements S3, . At S4, the diffracted light from the area H3 is focused at S6, and the diffracted light from the area H4 is focused at SS. Here, since the regions H1 and H2 play the same role as a knife, the focus error signal is generated by the light receiving element S1. It is obtained as a difference signal between S2, S, and S4. Also, the track error signal is in the area H3,
Since it is obtained as a difference in light amount intensity (push-pull signal) of light receiving element S5.H4. What is necessary is to find the difference signal of s6.

〔Effect of the invention〕

As explained above, the optical semiconductor device for optical disks of the present invention is made by hybridizing a semiconductor laser, a monitor light-receiving element, and a signal detection light-receiving element on a silicon substrate having a ■-shaped groove, thereby integrating these elements. By using the element of the present invention, a small and lightweight optical head can be constructed, and the speed of the optical disc can be increased.

FIG. 3 is a diagram illustrating the operating principle of an optical head using the optical semiconductor element of the present invention.

1... Silicon substrate, 2... V-shaped groove, 3... Semiconductor laser, 4, 5... Light receiving element, 6... Electrode, 1
o... Optical semiconductor element, 11... Lens, 12...
Hologram element, 13... Head cap, 14...
・Actuator.

Claims (1)

[Claims] A semiconductor laser is installed on a silicon substrate having a V-shaped groove so that its light emitting surface is parallel to the edge of the V-shaped groove, a first light receiving element that receives rear emitted light from the semiconductor laser, and a plurality of An optical semiconductor device for an optical disk, characterized in that a second light receiving element for receiving external light is formed on the silicon substrate.