JPS6035593A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the variation of laser output due to the reflection of monitor output light from a semiconductor laser, the formation of an external optical resonator, and the like by a method wherein the surface of a photo receiving element is provided in eccentricity so as not to include at least the main axis, and the other non-photo receiving part including the main optical axis is provided with a photo absorber for preventing reflection. CONSTITUTION:When the main optical axis of laser monitor output is OO' and the optical axis determined by points P and O on the surface of the photo receiving element 2 is OP, the position for monitoring the element 2 is deflected on the surface on a stem 5 is such a manner that the minimum valve of the angle made between the OO' and OP becomes 2.5 or more. Enlargement of the distance between O' and P in order that the angle made between the OO' and OP bacomes 2.5 deg. or more enables the reflection of monitor output light not to turn back to the end surface for outout oscillation of laser element, even if the angle of the photo receiving element surface inclines toward a laser chip. Further, carbon black, etc. is kept placed as the high photo absorber 8, or black paint containing carbon is kept applied, in order to prevent the irregular reflection from the stem surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to improvement of a semiconductor device including a semiconductor laser, a light receiving element, and the like.

[Background of the invention]

FIG. 1(a) is a schematic cross-sectional view showing a conventional semiconductor device.
bl is the view from above. That is, as shown in the figure, a semiconductor laser chip, a photodetector element 2. Submount 3. Heat sink 4. Stem or package 5
．． In the semiconductor device consisting of the cap 6 and the window glass 7, the light receiving element 2 receives the monitor output light of the laser.

When the monitor output light is received in order to control the output level of the semiconductor laser in this way, the reflection from the monitor light returns to the oscillation part of the laser element and forms an external resonator. Therefore, if there is a temperature change or a mechanical dimensional change, the far-field pattern of the output beam may be disturbed, or the oscillation longitudinal single mode and transverse fundamental mode may be partially distorted. This has been a big problem, especially when applied to video desks and the like, as it generates noise.

[Purpose of the invention]

The present invention has been made in view of the above points, and provides a semiconductor device that prevents variations in laser output due to reflection of monitor output light from a semiconductor laser, and the formation of external optical resonators. It is something.

[Summary of the invention]

In order to achieve the above object, in the present invention, the surface of the light receiving element is
At least, it is provided eccentrically so as not to include the main optical axis, and an antireflection light absorber such as carbon black is provided in other non-light receiving portions including the main optical axis.

[Embodiments of the invention and their effects]

Hereinafter, the present invention will be explained with reference to Examples.

As described above, in the present invention, the laser output beam is eccentrically centered with respect to the main optical axis so that only a portion of the laser output beam is received so that the reflected light from the surface of the light receiving element does not return to the monitor output section of the laser. This is where the light receiving element is placed.

FIG. 2 is a diagram showing an embodiment of the present invention.

As shown in the figure, a semiconductor laser element 1, a light receiving element 2, a submount 3. Heat sink 4. In the example of arranging the stem 5, when the main optical axis of the laser beam monitor output is OO' and the optical axis determined by the points P and 0 on the surface of the light receiving element 2 is OP, the minimum value of the angle between 00' and OF is The mounting position of the light receiving element 2 is deviated on the surface of the stem 5 so that the angle is 2.5° or more. This is due to the accuracy of the perpendicularity between the surface of the stem 5 and the surface of the laser chip l, and the accuracy of the parallelism of the solder attachment between the surface of the light receiving element 2 and the surface of the stem 5, etc. at a general technical level. Because it is about 2°.

Adjust the angle between 00' and OP to be 2.5° or more.
By leaving a distance between ' and P, even if the angle of the surface of the light-receiving element is inclined more than the laser chip, the reflection of the monitor output light is prevented from returning to the oscillation output end face of the laser element.

Further, in order to prevent diffused reflection from the stem surface, carbon black or the like is provided as a high light absorber 8, or a black paint containing carbon is applied. The area may include only the stem surface as shown in FIG. 2, but it may also include a part of the non-light receiving part of the light receiving element 2 (peripheral electrode part or a part without bonding), a part of the eaves, and a part of the surface of the heat sink 4. It may be applied to cover.

FIG. 3 is a diagram showing another embodiment of the present invention.

To prevent the laser monitor output from being reflected by the unused portion of the beam, as shown in the figure, on the submount 3,
Carbon bra as high light absorber 9.

The shielding area of the monitor output beam is configured to cover at least an area of about 2.5° centered on the main axis of the monitor output beam, or an area of 50 solid angles, depending on its height and width. It is something.

Since the main axis of the monitor output beam is cut, the optical power input to the photodetector decreases, but the alignment between the photodetector 2 provided on the surface of the stem 5 and the monitor output main optical axis of the laser element l If the angle deviation is within ±2°, there is no component reflected back to the laser element from the surface of the light receiving element. In addition, in the figure, 4 indicates a heat sink.

Further, the light absorber 9 has the effect of blocking reflected return components due to diffused reflection from the vicinity of the monitor output main optical axis. Note that the high light absorber described in the above embodiments is suitably made of carbon chips, carbon black, black paint, or the like.

[Brief explanation of the drawing]

FIG. 1 (Al is a schematic cross-sectional view showing a conventional semiconductor device. (BL is a view of the same from above, and FIGS. 2 and 3 are views each showing an embodiment of the present invention. l... Semiconductor laser element, 2... Light receiving element, 3... Submount, 4... Heat sink, 5... Stem,
6... Stem or package, 7... Window glass, 8
19...Light absorber. Representative Patent Attorney Akio Takahashi Figure 1 (Good) (b) Figure Z

Claims (1)

[Claims] 1. In a semiconductor device including a semiconductor laser and a light receiving element, the surface of the light receiving element is provided eccentrically with respect to the main optical axis of the monitor output light of the laser so as not to include at least the main axis; 1. A semiconductor device characterized in that an antireflection light absorber is provided in other non-light receiving portions including the main optical axis.