JPH04360593A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To suppress a level of stray light to be irradiated by reflection in a package for hermetically sealing a semiconductor laser element and to obtain an accurate output light with low noise by forming a light absorption film on the inner wall of the package. CONSTITUTION:In a semiconductor laser having a semiconductor laser element 1, and a package for hermetically sealing the element 1, formed partly of a light transmission member 6, light absorption films 7 made of black resin containing carbon for absorbing the optical output of the element 1, are formed on the inner surface of a stem 3 for hermetically sealing the element 1 and the inner surface of a cap 5. Thus, light emitted from the rear of the element 1 is directed to the stem 3 directly or after reflected on the surface of a submount 2 and absorbed by the film 7 provided on the surface. The light advanced to the inner surface of the cap 5 is also absorbed here, thereby reducing a reflected light component as compared with that of prior art.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device used as a light source for optical communication equipment, optical information processing equipment, optical sensors, and the like.

0002

2. Description of the Related Art FIG. 3 is a fragmentary sectional view of a conventional semiconductor laser device of this type. In the figure, 1 is a semiconductor laser element, 2 is a submount on which the semiconductor laser element is mounted, 3 is a stem that holds the submount 2 and leads 4, and 5 is a transparent plate 6 in the light transmitting part, and the semiconductor laser This is a cap that hermetically seals the device.

[0003] Here, the submount is made of Si or the like, and the stem and cap 5 are made of a material such as Covar or nickel, and their surfaces are plated with gold. Further, the transparent plate 6 is made of a stable material such as sapphire.

0004

In the conventional semiconductor laser device described above, the surfaces of the stem and cap are made of a material such as gold or nickel, so that the reflectance on the inner surface of the package is extremely high. The forward emitted light emitted from the resonator end face of the semiconductor laser element is directed toward the transparent plate 6, but a portion is reflected there. Further, the rear emitted light reaches the surface of the stem and is reflected there either directly or after being reflected on the surface of the submount. Further, a part of the emitted light from the laser element reaches the inner surface of the cap after being reflected directly or by other parts and is reflected there. These reflected lights are transmitted through the transparent plate and output together with the main emitted light of the laser element, but in conventional cases, the inner surface of the package is made of a material with high reflectance, so the level of the reflected light components is extremely high. Become something. Therefore, with conventional laser devices, the noise level is high and it is difficult to obtain accurate output light.

[0005]

[Means for Solving the Problems] The semiconductor laser device of the present invention includes a coating that absorbs the optical output of the laser element on the inner surface of the hermetically sealed stem and/or the inner surface of the cap. It was formed.

[0006]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a fragmentary sectional view showing one embodiment of the present invention. In the figure, 1 is a semiconductor laser element, 3 is a stem that supports a submount 2 and leads 4, 5 is a cap having a transparent plate 6, and 7 is a carbon-containing cap formed on the inner surface of the stem 3 and the cap 5. This is a light absorption film made of black resin.

In the embodiment shown in FIG. 1, light emitted from the rear of the semiconductor laser device 1 is directed toward the stem 3 either directly or reflected by the surface of the submount 2, and is absorbed by the light absorption film 7 provided on the surface. be done. Further, the light traveling to the inner surface of the cap 5 is also absorbed here. Therefore, with the above configuration, the reflected light component, which was included in the conventional example by several tens of percent, could be reduced to 1% or less.

FIG. 2 is a fragmentary sectional view showing another embodiment of the present invention. In this figure, parts that are equivalent to those in FIG. 1 are given the same reference numerals, so redundant explanation will be omitted. In this embodiment, the light absorption film 7 is applied to the inner surface of the transparent plate 6 except for the main emission light transmitting part.

With this configuration, it is possible to reduce the portion of the optical output from the semiconductor laser element 1 that exits from the transparent plate 6 due to reflection, and also to prevent re-reflection from the transparent plate 6.

Although the preferred embodiments have been described above,
The present invention is not limited to these examples, and for example, a metal compound film can be used as the material for the light absorption film 7 instead of a resin coating film. Further, a monitor light-receiving element that receives the backward emitted light may be arranged behind the laser element 1, or a multi-beam laser device may be constructed by arranging a plurality of laser elements.

[0011]

As explained above, the present invention forms a light absorbing film on the inner wall of a package that hermetically seals a semiconductor laser element. The level of emitted stray light can be suppressed, and a light source with less noise can be provided.

[Brief explanation of the drawing]

FIG. 1 is a fragmented cross-sectional view showing one embodiment of the present invention.

FIG. 2 is a fragmented sectional view showing another embodiment of the present invention.

FIG. 3 is a fragmented cross-sectional view of a conventional example.

[Explanation of symbols]

1...Semiconductor laser element 2...Submount 3...Stem 4...Lead 5...Cap 6...Transparent plate 7...Light absorption film

Claims (1)

[Claims] 1. A semiconductor laser device comprising a semiconductor laser element and a package, a part of which is constituted by a light-transmitting member and hermetically seals the semiconductor laser element, wherein a portion for extracting output light of the semiconductor laser element is provided. A semiconductor laser device characterized in that a light absorption film is formed on the inside of the package except for the package.