JPH01154584A - Array laser - Google Patents

Abstract

PURPOSE:To obtain a spot-shaped array laser adapted to be gradually cooled by so disposing at least one of light emitting units that the long axis of a far field pattern aligns in the same line as the long or short axis of a far field pattern of other light emitting unit. CONSTITUTION:An erasure laser chip 1 as an erasure light emitting unit is bonded obliquely at 90 deg. with respect to a conventional one toward a deep step of a heat sink plate 3a, and a recording/reproducing laser chip 2 is bonded in the same direction as a conventional one toward a shallow step. The depth of the step is suitably so designed that the light emitting points of the chips 1 and 2 are aligned on the same line and the long axis direction of the far field pattern of the chip 1 and the short axis direction of the far field pattern of the chip 2 are aligned on the same line. Accordingly, the long axis direction of the erasure radiating beam light becomes parallel to a track direction, and a recording material can be gradually cooled by the long axis radiating beam.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an array laser used as a light source for information processing equipment such as an optical disk memory.

[Conventional technology]

In an optical disk device that utilizes phase change, information is recorded, reproduced, and erased by utilizing the phase change between crystalline and amorphous recording materials.

To record information, first, a narrowed light spot is applied to a part of the recording material and the temperature is raised to melt the recording material and make the atomic arrangement random. Next, the light spot that is the heat source is removed, the heat is diffused into the substrate, and if it is cooled and solidified at once faster than the crystallization rate, it becomes an amorphous state.
A record has been made.

Information is erased by applying a light spot to the recording surface of the recording material, heating it up, melting the recording material once, and then slowly cooling it to crystallize it.

Information is reproduced by applying a low-output light spot to the recording surface and utilizing changes in the amount of reflected light due to the difference in reflectance between the amorphous state and the crystalline state.

In order to realize this erasing/recording/reproduction, it is necessary to form a long-axis optical spot for slow cooling during erasing and a short-axis optical spot for rapid cooling during recording on the same track of the optical disk.

Figures 3(a) and (b) show the conventional monolithic,
FIG. 2 is a side view showing a discrete array laser.

In this figure, 1 is an erasing laser chip, 2 is a recording/reproducing laser chip, and 3 is a heat sink.

Normally, with a single laser, whether monolithic or discrete, the optical disc must be rotated once after erasing before recording, but by forming an array, it is possible to record immediately after erasing.

Further, normally, the light emitting part of a semiconductor laser is long (for example, 2 to 3 μm) in the direction parallel to the junction and short (for example, 0.1 μm) in the direction perpendicular to the junction. Therefore, the far-field image of the light emitted from this part has an elliptical cross section that is short in the direction parallel to the junction and long in the direction perpendicular to the junction due to the influence of diffraction.

[Problems to be Solved by the Invention] In the conventional eye lasers as described above, the short axes of the laser beams are aligned on the same straight line, so the recording/reproducing and erasing spots are arranged along the track direction of the optical disc. When lined up, the long axes of the erase spots are perpendicular to the track direction.

However, this method requires slow cooling in the direction of the short axis of the erased spot, so a sufficient slow cooling effect cannot be obtained, and unerased and
There was a problem that problems such as unerased areas occurred.

The present invention was made to solve this problem, and an object of the present invention is to obtain an array laser with a spot shape suitable for slow cooling.

[Means for solving problems]

In the array laser according to the present invention, at least one of the light emitting parts is arranged such that the long axis of the far field image is aligned with the long axis or short axis direction of the far field image of the other light emitting parts. It is.

[Effect]

In this invention, by arranging the erasing light emitting section so that the long axis direction of the far-field image is parallel to the track direction, it becomes possible to perform slow cooling at the erasing spot.

〔Example〕

FIG. 1 is a side view showing an embodiment of the array laser of the present invention.

In this figure, the same symbols as in Figs. 3(a) and (b) indicate the same parts, and 3a is a heat sink with two steps.
The one where the erasing laser chip 1 is bonded is deeper, and the other is shallower.

In this embodiment, an erasing laser chip 1 as a light emitting part for erasing is tilted by 90'' with respect to the conventional example and bonded to the deep step of the heat sink 3a, and a recording/reproducing laser chip 2 is bonded to the shallow step. is bonded in the same direction as the conventional example.By appropriately designing the depth of the step, the light emitting points of the erasing laser chip 1 and the recording/reproducing laser chip 2 are aligned on the same line, and the erasing The long axis direction of the far field image of the laser chip 1 for reproduction and the short axis direction of the far field image of the laser chip 2 for reproduction can be arranged on the same line.

Therefore, the long axis direction of the emitted erasing beam becomes parallel to the track direction, and the recording material can be slowly cooled by this long emitted beam.

In the above embodiment, only the erasing laser chip 1 is 90°.
Although it was assembled by rotating the recording/reproducing laser chip 2, if the recording/reproducing laser chip 2 has a small aspect ratio of the emitted beam, the recording/reproducing laser chip 2 can also be rotated 90 degrees so that the long axes are the same as shown in Fig. 2. They may be assembled by arranging them in a line.

Further, in the above embodiment, a two-point array laser has been described, but it is also possible to use a three-point or more array laser, for example, for erasing/recording/reproducing or melting/erasing/recording/reproducing.

Further, in the above embodiment, the assembly was explained using a junction-up method (the substrate side is bonded to the heat sink), but the same effect can be obtained even if the assembly is performed using a junction-down method.

〔Effect of the invention〕

As explained above, the present invention is characterized in that at least one of the light emitting parts is arranged so that the long axis of the far field image is aligned with the long axis or the short axis direction of the far field image of the other light emitting parts. This has the advantage that erasing and recording can be performed continuously and accurately with a simple optical system and a simple drive system.

[Brief explanation of the drawing]

FIG. 1 is a side view showing one embodiment of the array laser of the present invention, FIG. 2 is a side view showing another embodiment of the invention, and FIG.
The figure is a side view showing a conventional array laser. In the figure, 1 is an erasing laser chip, 2 is a recording/reproducing laser chip, and 3a is a heat sink. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa (2 others) Figure 1 Figure 2

Claims (1)

[Claims] In an array laser having at least light-emitting sections for erasing and recording/reproducing in the same package, the long axis of the far-field image of at least one of the light-emitting sections is such that the long axis or short axis of the far-field image of the other light-emitting section is An array laser characterized by being arranged on the same line as the axial direction.