JPH0576706B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Technology) The present invention relates to an optical recording and reproducing method for recording and reproducing data using a traveling recording medium having track guide grooves and an optical head.

(Prior Art) The present inventors have previously made an invention related to an optical head and are currently applying for a patent (Japanese Patent Application No. 166,731/1983). An optical recording/reproducing method using this optical head will be explained with reference to FIG. 1 is a semiconductor laser, 2-1, 2-2
3 is a photodetector, 3 is a branched optical waveguide, 3-1 is an open end of the branched optical waveguide 3, 3-2 is an open open end, 4
5 is a substrate, 5 is a laser beam emitted from the open opening end 3-2, 6 is a grooved running recording medium, 7 is a recording layer with a protective film, and 8 is a slider bearing.

The laser beam emitted from the semiconductor laser 1 is
The light enters the branched optical waveguide 3 embedded in the substrate 4 through the open end 3-1, and exits through the open open end 3-2. During recording, high laser power is irradiated and data is recorded along the grooves by changes in reflectance. During reproduction, a low laser power is applied and reflected light from the running recording medium 6 is detected. Since the cross-sectional shape of the groove is nearly rectangular, the medium irradiation light is largely reflected in the vertical direction and returns to the branched optical waveguide 3. Light whose intensity changes according to the data string is detected by a photodetector 2-2.

(Problems to be Solved by the Invention) In such an optical recording/reproducing system, the light returned to the semiconductor laser 1 interferes with the oscillated light within the laser resonator, causing fluctuations in the output of the laser. To prevent this, (i) increase the number of branches of the optical waveguide 3,
(ii) The refractive index n of the branched optical waveguide 3 on the photodetector side is made larger than the refractive index n on the semiconductor laser side. Methods such as reducing the amount of light returning to the semiconductor laser 1 have been considered. However, with this method, there are problems such as (1) the manufacturing process of the head becomes complicated, and (2) the transmission efficiency from the semiconductor laser to the optical waveguide is 50 to 80%, reducing the laser power for irradiating the medium. The dot was hot.

(Structure of the Invention) In order to solve the above-mentioned problems, the present invention includes a traveling recording medium having track guiding grooves and an optical head in which photodetectors are arranged on both sides of a laser light source.
floating the optical head close to the traveling recording medium;
In an optical recording and reproducing method for recording and reproducing data, grooves having a V-shaped cross section and an apex angle of 140° or more and 150° or less are continuously formed in a direction perpendicular to the traveling direction of the traveling recording medium. , data is recorded on the peaks or valleys of the V-shaped groove, and signal reproduction is performed by receiving reflected light from the peaks or valleys with photodetectors placed on both sides of the laser light source. It is characterized by

(Function) According to the above configuration, the reflected light of the laser beam from the laser light source is concentrated on the photodetectors located on both sides, so that the amount of light returning to the laser light source is reduced.

(Embodiment) FIG. 1 shows a first embodiment of the present invention, in which the same components as those of the conventional example are denoted by the same reference numerals. 1 is a semiconductor laser as a laser light source, 2-1, 2-
2 is a photodetector provided on both sides of the semiconductor laser 1;
5 is a substrate, 5 is a laser beam, 6 is a running recording medium with track guide grooves, 7 is a recording layer with a protective film, 8 is a slider bearing, 9 is a groove with a V-shaped cross section, which is perpendicular to the running direction of the running recording medium 6. It is formed continuously in the direction of Optical head (semiconductor laser 1, photodetector 2-
1, 2-2, and the substrate 4) are installed on the slider bearing 8 as in FIG.

During recording, the laser beam 5 emitted from the semiconductor laser 1 follows the peak 9a of the V-shaped groove 9, and records data on the medium as a change in reflectance or a change in refractive index by intensity modulation. At this time, the reflected light from the mountain portion 9a is separated into left and right sides by the slope.
Therefore, the reflected light in the direction perpendicular to the medium, that is, the light returning to the semiconductor laser 1, is significantly suppressed due to the shape effect of the groove.

Possible recording media include perforated recording media such as metals and amorphous thin films, or recording media based on chalcogenite materials whose recording mechanism is phase transformation between crystal and amorphous.

During reproduction, the laser beam 5 emitted from the semiconductor laser 1 follows the peak 9a of the V-shaped groove 9, and
The reflected light from a is separated into left and right sides by the slope, and detected by photodetectors 2-1 and 2-2 corresponding to each slope. Therefore, the reflected light in the direction perpendicular to the medium, that is, the light returning to the semiconductor laser 1, is significantly suppressed by the shape effect of the groove. As an example,
Irradiates a V-shaped groove with a beam radius of 2.0 μm, and
The second calculation result of the reflected diffraction light intensity distribution at 3.0μm
As shown in the figure. The calculation used the Fresner-Kirchhoff integral, and the light intensity distribution in the near field was determined by numerical calculation. The horizontal axis is the coordinate on the photodetector, and the vertical axis is the relative intensity. As the V-groove angle θ increases, the amount of reflected light in the vertical direction decreases.

The permissible range of the V-groove angle θ is determined by the permissible condition of the amount of light returned to the semiconductor laser, but it should be approximately 15° or more.
It is sufficient if the apex angle of the V shape is 20° or less, or in other words, the apex angle of the V-shape is in the range of 140° or more and 150° or less.

The track signal is detected by the differential outputs of photodetectors 2-1 and 2-2. When the laser beam 5 deviates from the center of the V-shaped groove 9, the intensity distribution of reflected and diffracted light by the V-shaped groove 9 becomes asymmetric, and the photodetectors 2-1,
The laser power incident on 2-2 is different.

As an example, FIG. 3 shows the difference in the intensity distribution of reflected diffracted light when the amount of positional shift is 0.5 μm. On the media surface
Even at 3.0 μm, an asymmetric light distribution occurs and track signal detection becomes possible. According to the track signal detected in this way, the head arm on which the slider bearing 8 shown in FIG. 1 is installed, for example, is driven, and track control is performed.

Focus control is performed by installing the entire optical head on the end face of the slider bearing 8 shown in FIG. 1 and utilizing air levitation. The air levitation effect of the slider bearing 8 is the same as that of a floating head slider bearing used in a magnetic disk, so a description thereof will be omitted here. The flying distance from the traveling recording medium 6 is set based on the required beam diameter on the traveling recording medium 6. Such a floating head system allows focus control without using a focus actuator in conventional devices.

In the embodiment described above, data is recorded following the peaks 9a of the V-shaped groove 9, but data may be recorded following the valleys 9b of the V-shaped groove 9 and then reproduced. The same effects as in the embodiment described above can be obtained.

FIG. 4 shows a method of manufacturing the optical head. In FIG. 4, 10 is p-GaAs and 11 is p-GaAs.
AlGaAs, 12 is GaAs, 13 is n-AlGaAs,
14 is n-GaAs, and a semiconductor laser and a photodetector are integrally formed on the substrate 14. Reference numeral 15 denotes an electrode, which is made of Au-Cr, Au-Ge-Ni, or the like. After producing such a layer by multilayer epitaxial growth, a trench 16 with a width of approximately 1 μm is provided as shown in FIG. Insulate. The center part (solid diagonal line) is the laser emitting part,
The left and right p-n junctions (dotted diagonal lines) are given a reverse bias and become photodetectors. A method for providing the trench is, for example, drilling by ion milling.

(Effects of the Invention) As explained above, according to the present invention, the optical head is provided with a traveling recording medium having a track guide groove and a photodetector disposed on both sides of a laser light source, and the optical head is In an optical recording and reproducing method in which data is recorded and reproduced by floating close to the recording medium,
A groove with a V-shaped cross section and an apex angle of 140° or more and 150° or less is continuously formed in the direction perpendicular to the running direction of the running recording medium, and the groove is formed in the peaks or troughs of the V-shaped groove. Since data is recorded and signals are reproduced by receiving the reflected light from the peaks or valleys with photodetectors placed on both sides of the laser light source, the laser light irradiated onto the running recording medium is Almost no light returns to the laser, so stable recording and playback can be achieved without the need for a means to prevent return light as in conventional systems, and symmetrical reflected light can be obtained on the two photodetectors. Since a track signal is thus obtained, there is an advantage that an optical recording/reproducing apparatus with a simple configuration can be realized.

[Brief explanation of the drawing]

Fig. 1 is a head medium configuration diagram showing an embodiment of the present invention, Fig. 2 is a graph explaining the dependence of the light intensity distribution on the V-groove angle, and Fig. 3 is the light intensity distribution at a positional deviation of 0.5 μm. FIG. 4 is a diagram of the structure of an optical head, and FIG. 5 is a schematic diagram of the structure of an optical head and a recording medium for explaining a conventional optical recording/reproducing system. 1... Semiconductor laser, 2-1, 2-1... Photodetector, 4... Substrate, 5... Laser beam, 6...
Grooved running recording medium, 7... Recording layer with protective film, 8
...Slider bearing, 9...V-shaped groove.

Claims (1)

[Scope of Claims] 1. A traveling recording medium having a track guide groove and an optical head having photodetectors arranged on both sides of a laser light source, the optical head being levitated close above the traveling recording medium, and data In an optical recording and reproducing method for recording and reproducing, continuously forming grooves having a V-shaped cross section and an apex angle of 140° or more and 150° or less in a direction perpendicular to the traveling direction of the traveling recording medium, Data is recorded on the peaks or valleys of the V-shaped groove, and signal reproduction is performed by receiving reflected light from the peaks or valleys with photodetectors placed on both sides of the laser light source. Characteristic optical recording and reproducing method.