JPH01222492A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To enable the manufacture of a device at a low cost by a method wherein a silicon film whose thickness is 7/100-8/100 of a wavelength is coated on an aluminum film coated on an end face whose thickness corresponds to one-fourth of a wavelength, which are sealed with a transparent plastic resin of a refractive index of 1.3-1.6. CONSTITUTION:A semiconductor laser element 1 and a photodiode 3 are buried in a transparent plastic resin 2 in place of a cap provided with a window glass. In this process, an aluminum film 7 1/4 as thick as a wavelength and a silicon film 8 7/100-8/100 as thick as a wavelength are laminated on both the end faces of the passivation film of the laser element 1, whereby the refrectivity of both the end faces decreases to about 32% when the element 1 is buried in the resin of a refractive index of 1.3-1.6. Therefore, a laser oscillating threshold current and a differential quantum efficiency of the element 1 are made equal to those of a conventional element, so that the element 1 does not vary in characteristic. By these processes, a package can be decreased in cost, a divergence angle can be controlled, and the element is also excellent in heat dissipation and hermetic sealing.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a semiconductor laser device used as a laser light source for optical disk devices such as compact disks and optical information processing devices such as laser printers.

2. Description of the Related Art] Taking a semiconductor laser used in a compact disc as an example, a cross-sectional structural diagram thereof is shown in FIG.

The semiconductor laser device 1 has the same end face reflectance so that optical output can be obtained from both end faces. That is, normally, the reflectance is about 32%, which is the same as when the crystal is open.
Alumina is passivated on the end face with a film thickness equivalent to half a wavelength. The light emitted from one end face is received by a photodiode 3 to obtain a monitor signal of optical output. The semiconductor laser element 1 and photodiode 3 are mounted on a base 4 and connected to the outside through lead wires 6. The base 4 is sealed with a cap 9 having a window glass 1o, and dry nitrogen gas is sealed in the cap.

Problems to be Solved by the Invention Semiconductor laser devices have come to be used in compact disks, and mass production has begun, and today the number of devices produced has reached 10 million units per year. As mass production progresses, the cost of the elements themselves has steadily declined.

This is because, like other semiconductor devices, mass production effects can be expected. However, the costs of the bases and caps on which the elements are mounted have not been reduced.

That is, it uses a gold-plated base and a cap with a window glass with high surface precision. In order to reduce the cost of mounting, there is a resin sealing method that is already used for light emitting diodes.

In this case, the refractive index of the plastic resin is 1.3 to 1.
6, so if a laser element with the arm opening as it is is embedded in resin, the end face reflectance will drop to 16 to 22%. As a result, the threshold current for laser oscillation increases and reliability deteriorates. Therefore, even if it is embedded in resin, it is necessary to perform end face passivation so that the reflectance is 32%.

Means for Solving the Problems The semiconductor laser device of the present invention has an alumina film on the end face having a film thickness corresponding to a quarter wavelength (where λ is the wavelength and n is the refractive index, the film thickness d=λ/ 4n), is coated with silicone with a thickness of 7 to 8 hundred wavelengths, and is sealed with a transparent plastic resin with a refractive index of 1.3 to 1.6. There is.

Function When the refractive index of the plastic resin is 1.3, the reflectance is approximately 32% when the thickness of the second layer silicon film is 7/100 wavelengths, and slightly greater than 32% at 8/100 wavelengths. Become. In addition, if the refractive index of plastic is 1.6, the reflectance of the second layer silicon film is approximately 32% at 8/100 wavelengths, and 32% at 7/100 wavelengths. It becomes a little smaller. Therefore, at a film thickness of 7% to 8% wavelength, approximately 32%
A reflectance of

Embodiment FIG. 1 shows a sectional view of a semiconductor laser device according to an embodiment of the present invention. Unlike the conventional semiconductor laser device shown in FIG. 3, a transparent plastic resin 2 is used instead of a cap with a window glass to connect the semiconductor laser element 1 and photodiode 3.
is embedded.

The second enlarged view of the panbage eye film of semiconductor laser device 1 is
As shown in the figure. Alumina coating with a quarter wavelength film thickness is applied to both end faces.
By laminating the silicon film 8 with a thickness of 7% to 8% of the wavelength, the reflectance of both end faces has a refractive index of 1.3.
It becomes about 32% when embedded in 1.6 resin. Therefore, the threshold current for laser oscillation and the differential quantum efficiency are the same as those of conventional elements, and the laser characteristics remain unchanged. however,
The angle of refraction becomes small at the interface between the resin and air, so if the resin has a flat shape, the beam spread υ angle becomes narrower.

Therefore, by giving the tip of resin 2 an appropriate curvature,
The spread υ angle and spread υ of the emitted light from the semiconductor laser element 1
It is also possible to change the aspect ratio of the corners.

Effects of the Invention According to the semiconductor laser device of the present invention, it is possible not only to reduce the cost of the package, but also to control the divergence angle, which is excellent in terms of heat dissipation and airtight sealing, and is compact and compact. This has great effects when applied to disks, etc.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a semiconductor laser device of the present invention, FIG. 2 is a diagram showing end face percipation of a laser element, and FIG. 3 is a sectional view of a conventional semiconductor laser device. 1...Semiconductor laser element, 2...Transparent plastic resin, 3...Photodiode, 4
...Pace, 6...Lead line, 6...
... Semiconductor laser crystal, 7 ... Alumina film, 8 ... Silicon film. Name of agent: Patent attorney Toshio Nakao and 1 other person/-
- One cow' 14 Leah Shuko 2 - - Transparent plastic 1 3 - Photothane ode Hajime - Base 6 - Semi-thin 5-ray fs @ Todoroki 1 - Meridian drape element 3 --- Photothane ode 4 −・−Heas δ−・So)Special de−cap

Claims (1)

[Claims] An alumina film is formed on at least one of the end faces of the resonator to a thickness corresponding to one-fourth of the oscillation wavelength, and a silicon film is formed on top of the alumina film to a thickness corresponding to one-fourth of the oscillation wavelength. A semiconductor laser device characterized in that a semiconductor laser element formed to a corresponding thickness is sealed with a transparent resin having a refractive index of 1.3 to 1.6.