JPH05135396A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To surely prevent a return noise without applying a coating for preventing reflection, etc., by using a semiconductor laser formed with a stripe diagonally with the laser output end face, thereby constituting a laser pickup device. CONSTITUTION:A laser pickup 1 is constituted by using a semiconductor laser 2 formed with a stripe 3 diagonally with the laser output end face. Since the laser beam emitted from the semiconductor laser 2 of the laser pickup 1 is diagonally emitted from the end face, the reflected light returning by being reflected with an optical system 4 is made incident diagonally on the end face of the semiconductor laser 2. Then, the light reflected from the end face of the semiconductor laser 2 does not pass the same optical path and is not made incident again on the optical system 4. As a result, the return noise is surely prevented without applying coating for preventing reflection, etc., on the end face of the semiconductor laser 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser used in a laser pickup and a laser pickup device using the semiconductor laser.

[0002]

2. Description of the Related Art Conventionally, a laser pickup 10 as shown in FIG. 2 has been used in a laser pickup device. The stripe 12 of the semiconductor laser 11 used in the laser pickup 10 is formed perpendicular to the laser output end face as shown in FIG. The laser beam emitted from the semiconductor laser 11 thus configured to the optical system 13 is diffracted by the diffraction grating 14 into three beams of the main beam P ₀ and the auxiliary beams P ₁ and P ₂ , and the beam splitter 15 and the objective The light enters the disk D through the lens 16.
The beam incident on the disk D is reflected by the disk D and becomes beams P ₀ ′, P ₁ ′, and P ₂ ′, which reverse the original optical path and reach the beam splitter 15. Most of these return beams P ₀ ′, P ₁ ′, and P ₂ ′ are reflected by the beam splitter 15, pass through the concave lens 17 and the cylindrical lens 18, and reach the photosensor 19.

However, the return beams P ₀ ′, P ₁ ′, P ₂
A part of ′ passes through the beam splitter 15 and returns to the semiconductor laser 11. These transmitted lights are reflected by the end surface of the semiconductor laser 11 and return to the optical system 13 again. When the composite resonator is formed between the semiconductor laser 11 and the optical system 13 as described above, it causes noise (hereinafter referred to as return noise). For this reason, the reflectivity of the end face of the semiconductor laser 11 is reduced, the end face is coated with a film having a low reflectivity, or the end face of the semiconductor laser 11 is etched to change its shape, so that the end face re-reflection light amount We are trying to reduce it. In the figure, the arrow indicates the optical path.

However, such conventional means cannot reduce the amount of re-reflected light on the end face, but cannot eliminate the return noise.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and by setting the end face re-reflected light amount to substantially zero, return noise can be reliably prevented. An object of the present invention is to provide a semiconductor laser and a laser pickup device using the same.

[0006]

The semiconductor laser of the present invention is a semiconductor laser used in a laser pickup, and is characterized in that stripes are formed obliquely with respect to the laser output side end face.

A laser pickup device of the present invention is characterized by using the semiconductor laser.

[0008]

In the semiconductor laser of the present invention, since the stripes are formed obliquely with respect to the laser output end face, the light reflected from the optical system is reflected at the laser output end face and again enters the optical system. Since it does not enter, return noise can be reliably prevented.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited to such embodiment.

FIG. 1 is an explanatory diagram of an embodiment of the present invention.
In the figure, 1 is a laser pickup, 2 is a semiconductor laser, 3 is a stripe, and 4 is an optical system. The arrow indicates the optical path.

The semiconductor laser 2 is the same as the conventional semiconductor laser except that the stripes 3 are obliquely formed on the laser output end face as shown in the figure, and therefore the detailed description of the structure is omitted. Further, since the optical system 4 is also the same as the conventional one, detailed description of its configuration is omitted.

The laser pickup 1 thus constructed
In the above, since the laser beam emitted from the semiconductor laser 2 is obliquely emitted from the end face, the reflected light reflected and returned by the optical system 4 is obliquely incident on the end face of the semiconductor laser. Therefore, the light reflected from the end face of the semiconductor laser does not pass through the same optical path and does not enter the optical system 4 again (see FIG. 1).

[0013]

As described above, in the present invention, since the light reflected from the optical system does not enter the optical system again, the return noise is eliminated without applying an antireflection coating or the like to the end face of the semiconductor laser. It can be surely prevented.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an optical path according to an embodiment of the present invention.

FIG. 2 is a schematic view of a conventional laser pickup.

FIG. 3 is an optical path diagram of a conventional laser pickup.

[Explanation of symbols]

 1 Laser pickup 2 Semiconductor laser 3 Stripe 4 Optical system

Claims (2)

[Claims] 1. A semiconductor laser used in a laser pickup, wherein a stripe is formed obliquely with respect to a laser output end face. 2. A laser pickup device comprising the semiconductor laser according to claim 1.