JPH03217067A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To enable quantity of light entering a monitor PD to be constant and controllability of laser light to be enhanced by forming a PbSn solder to be formed on a surface where a LD chip of a submount is bonded smaller than the area of the LD chip and by allowing a surface without solder to be coated with a metal whose surface state is stable such as gold. CONSTITUTION:In a semiconductor laser device where an LD chip 1 is assembled into a cooling block through a submount 2 as a heat stress relaxing material, a PbSn solder 10 is formed on a surface where the LD chip 1 of the submount 2 is bonded smaller than the area of the LD chip 1 and the surface of the submount 2 without the PbSn solder 10 is coated with a metal 11 whose surface state is stable such as gold, thus enabling light applied from the rear surface of the LD chip 1 to be reflected from a metal 11 whose surface state is stable such as gold and a certain amount of light to enter a monitor PD stably for improving controllability of light applied from laser.

Description

[Detailed Description of the Invention] [Industrial Application Field 1] The present invention relates to a semiconductor laser device in which a laser diode (hereinafter abbreviated as LD) chip is assembled via a submount serving as a thermal stress relaxation material. be.

[Conventional technology]

FIG. 3 is a cross-sectional front view showing a conventional semiconductor laser device.
The LD chip (1) is assembled into a heat dissipation block (3) via a submount (2) serving as a thermal stress relaxation material, and the heat dissipation block (3) is assembled into a stem (5) into which a monitor PD chip (4) is incorporated. It is assembled in.

The LD chip (1) and the PD chip (4) are bonded with a gold wire (6) and are electrically connected to a lead wire (7). A cap (8) is attached to the stem (5),
The LD is composed of an LD chip (1) as shown in FIG.
) to improve its thermal characteristics, the LD chip (
Junction down so that the active layer (9) of 1) is on the submount (2) side.
PbS1:l solder (1) is applied to both sides of the submount (2), which is assembled using the
0) is formed, and the LD chip (1), submount (2), and heat dissipation block (3) are bonded thereto.

Next, the operation will be explained.

The LD chip (1) is connected to the lead wire (7). When Kt pressure is applied, a current flows through the LD chip (1) and laser oscillation begins, and laser light is emitted from the LD chip (1) in two directions as shown in Figure 3. It is radiated as shown by the arrow. One laser beam is used as the light source of the optical system, and the other laser beam is used as a monitor P.
The monitor PD (4), which is used to control the LD light output and is incident on D (4), is tilted with respect to the laser as shown in the figure, and the incident laser light is reflected by the PD (4). It is assembled so that it will not enter the LD chip (1) again.

[Problems to be Solved by the Invention] Since the conventional semiconductor laser device was constructed as described above, the active layer was assembled close to the submount, and the light emitted from the back surface of the LD chip was caused by a PbSn-based laser. It will be reflected on the solder surface and will be incident on the monitor PD (4).
In the case of PbSn-based solder, good adhesion can be obtained, and since it is a soft solder, it has the advantage of reducing assembly stress on the LD chip. It was difficult to keep the amount of light incident on the monitor PD constant (due to changes in reflectance due to roughness, etc.), and problems were likely to occur in the controllability of the laser light.

The present invention has been made in order to solve the above-mentioned problems, and its purpose is to improve the controllability of laser light by making the amount of light incident on the monitor PD constant even in PbSn-based solder. Means for Solving the Problem] A semiconductor laser device according to the present invention has a submount LD.
Phon-based solder is LD on the surface where the chip is attached.
It is formed smaller than the area of the chip, and the areas without solder are covered with a metal such as gold whose surface condition does not change over time.

[Effect 1] In the semiconductor laser device of the present invention, the light emitted from the back surface of the LD chip does not enter the PbSn solder and is reflected, but is reflected by a metal with a stable surface state such as gold.
The incident light on the monitor PD remains constant.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. Figs. 1 and 2 are a plan view and a front view of a semiconductor laser device which is an embodiment of the present invention. As shown in the figure, a submount (
2) On the side where the LD chip (1) is mounted, there is a PbSn solder (10) smaller in area than the LD chip (1).
is formed and placed, and the surfaces other than the PbSn solder (10) are covered with a metal (11) with a stable surface condition such as gold. The other surface of the submount (2) is entirely coated with PhSr'l solder (10).

Align the LD chip (1) and submount (2) on a heat dissipation block (not shown) and heat up the PbS.
Adhesion is performed using n-based solder (10).

Next, I will explain the operation.The light emitted from the back surface of the LD chip (1) is emitted from a metal (1) with a stable surface condition such as gold on the submount (2) as shown in Figure 2.
1) and enters the monitor PDL (not shown).

[Effects of the Invention] As described above, according to the present invention, the PbSn solder area on the surface of the submount to which the LD chip is bonded is formed to be smaller than the LD chip area, and the surface other than the PbSn solder is made of gold or the like. Since it is covered with a stable metal, a constant amount of light emitted from the back side of the LD chip enters the monitor PD in a stable manner, improving the controllability of the laser emitted light.

[Brief explanation of drawings]

1 and 2 are a plan view and a front view of a semiconductor laser device that is an embodiment of the present invention, FIG. 3 is a cross-sectional front view of a conventional semiconductor laser device, and FIG. 4 is an LD chip of FIG. 3. and an enlarged front view of the submount. In the figure, (1) is the LD chip, (2) is the submount, (10) is Phon solder, and (11) is metal such as gold. show.

Claims (1)

[Claims] In a semiconductor laser device configured by assembling an LD chip onto a heat dissipation block via a submount as a thermal stress relaxation material, the surface of the submount to which the LD chip is bonded is made of Pb.
Sn-based solder is formed to be smaller than the area of the LD chip,
A semiconductor laser device characterized in that the submount surface without PbSn solder is covered with a metal having a stable surface condition, such as gold.