JPH02213189A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To lessen the number of components, to reduce position adjustment of the components as much as possible and also to reduce the cost by a method wherein a laser diode chip emitting a laser light to enter each beam splitter is formed in a submount and installed on a plane whereon photodiodes for signal regeneration and monitoring are formed or at a position higher than the plane. CONSTITUTION:An N-type semiconductor substrate 16 is used as a submount in which an LD chip 1 is incorporated, P-type diffused regions are formed in two places within the same plane of this semiconductor substrate 16, and these regions are made to be a photodiode(PD) 14 for signal regeneration and PD 4 for monitoring. Besides, beam splitters 17 and 18 are installed on the PD 14 for signal regeneration of the semiconductor substrate 16 and incorporated in a stem 5. An emitted laser light from the LD chip 1 is split into a rectilinear light and a 90 deg.-reflected light by the beam splitter 17, and the rectilinear light is turned to be a 90 deg.-reflected light by the beam splitter 18, made to enter the PD 4 and used for control of the laser light. The reflected light at the beam splitter 17 is applied to a disk, and the reflected light turned to be a signal light enters the beam splitter 17 and then the PD 14, whereby a signal is regenerated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a signal reproducing photodiode (hereinafter referred to as PD).
The present invention relates to a semiconductor laser device (hereinafter abbreviated as LD) that incorporates a monitor PD (abbreviated as LD) and a PD for monitoring.

[Conventional technology]

FIG. 4 shows the configuration of a conventional LD. In Figure 4, L
The D-chip 1 is assembled to a heat radiation block 3 via a submount 2 serving as a thermal stress relaxation material, and the heat radiation block 3 is assembled to a stem 5 in which a monitor PD 4 is incorporated. LD chip 1 and monitor PD 4 each have gold wire 6
is bonded and electrically connected to the lead wire 7. A cap 8 is attached to the stem 5, and the LDl
oo is configured.

This LDloo is built into a pickup and used as a light source for reading optical discs such as audio discs and video discs.

Next, the configuration of the pickup is shown in FIG. A collimating lens 9 is installed in front of the LD 100, a polarizing beam splitter 10, a 174-wave plate 11° objective lens 12. Is
Bundle lens 13. PD14 for signal reproduction and optical disc 1
5 constitutes a pickup 200.

Next, the operation of the conventional LDloo and pickup 200 will be explained.

In the LDloo shown in the 4th WJ, when a voltage is applied to the lead wire 7, a current flows to the LD chip 1 and laser oscillation starts (I), and laser light is emitted from the LD chip 1 in two directions as shown by the arrows in the figure. Ru. One laser beam is used as a light source for reading optical discs, and the other laser beam is used for monitoring P
The light enters D4 and is used to control the LD light output. The monitor PD 4 is inclined with respect to the laser beam, and is assembled so that the incident laser beam is reflected by the monitor PD 4 and does not enter the LDI again.

In the pickup 200 shown in FIG. 5, the laser light emitted from the LDloo passes through the frimate lens 9 and becomes parallel light, and then passes through the polarization beam stabilizer 10 and becomes direct spa light.9 It then passes through the 174 wavelength plate 11 and becomes circularly polarized light. . The objective lens 12 focuses the light onto an optical disk 15 into a light spot. The light spot is weakened at the bit portion of the optical disk 15, and the light reflected from the land portion without being weakened passes through the objective lens 12 and becomes a parallel beam. Also, 174
After passing through the wavelength plate 11, the reflected light becomes direct 1JjIliil light whose return direction is different from the outgoing direction, and the reflected light reflected by the polarizing beam stabilizer 10 enters the converging lens 13 into the PD 14 for facultative signal reproduction, and the signal Playback occurs.

[Problem to be solved by the invention]

As shown in FIG. 5, the conventional pickup 200 has the drawbacks of a large number of parts and a high price. Additionally, there is a drawback that position adjustment of parts is required to obtain the required performance.

The present invention has been made to solve the above-mentioned conventional drawbacks, and aims to provide an inexpensive semiconductor laser device with a reduced number of parts and the need for positional adjustment of parts as much as possible.

[Means to solve the problem]

In the semiconductor laser device according to the present invention, a signal reproducing photodiode and a monitoring photodiode are formed in the same plane of a submount as a thermal stress relaxation material, and a signal reproducing photodiode and a monitoring photodiode are formed on the same plane. The beam splitter on the signal regeneration photodiode is installed so that the incident light is reflected in the opposite direction to the signal regeneration photodiode, and the beam splitter on the monitor photodiode is installed so that the incident light is reflected in the opposite direction to the signal regeneration photodiode. A flat surface on which a signal regeneration photodiode and a monitor photodiode are formed, which is installed so that it is incident on the monitor photodiode, and a laser diode chip that emits laser light that is incident on each beam splitter is formed on a submount. It is installed at a required position above or higher than the plane of B.

[Effect]

In this invention, since the monitoring photodiode and the signal reproducing photodiode are incorporated into the submount with high positional accuracy, the number of component position adjustments during pickup assembly is reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a semiconductor laser device showing an embodiment of the present invention before it is assembled into a stem. Two p-type diffusion regions are formed in the same plane using photolithography and diffusion techniques, and these are used as a signal reproducing PD 14 and a monitoring PD 4.

Further, the LD chip 1 is assembled on the semiconductor substrate 16, and beam splitters 17 and 18 are installed on each of the signal reproducing PDs 14 on the semiconductor substrate 16. After this, as shown in Figure 2 (
Incorporate into stem 5.

In the semiconductor laser device of the present invention configured as described above, the signal reproducing PD 14 and the monitoring PDd are integrally formed within the same plane of the semiconductor substrate 16 as a submount, and the The emitted laser beam is divided into straight light and 90° reflected light by the beam splitter 17, and the straight light becomes 90° reflected light by the beam splitter 18, which enters the monitoring PD 4 and is used to control the laser light. The reflected light from the beam splitter 17 is irradiated onto the disk, and the reflected light, which has become signal light, is incident on the beam splitter 17 and then incident on the signal reproducing PD 14, where the signal is reproduced.

The beam splitter 17 uses reflected light as a PD for signal reproduction.
The beam splitter 18 must be installed so that the reflected light is incident on the monitor PD 4.

In addition, since only the output light from one end face is used for the light emitted from the LD deep 1, the output light from the other end face is 100%
to increase the output efficiency.

Furthermore, the beam splitter 18 also has a reflectance of 100% to increase the incidence efficiency to the monitoring PD 4 and to prevent signal light from the disk from entering again.

Furthermore, silicon is suitable for the semiconductor substrate 16.
It is also suitable as a thermal stress relieving material and when using both PD4°14.

3(a) and 3(b) are diagrams showing another embodiment of the present invention, in which the embodiment of FIG. 1 incorporates the LD chip 1 on the surface of a flat semiconductor substrate 16. In this embodiment, the LD chip 1 is installed at a position higher than the surface of the submount.

That is, the laser light actually emitted from the LD chip 1 is emitted with a wide spread, and the thickness of the LD chip 1 is about 100 μm, so it is necessary to prevent the laser light from being vignetted on the surface of the semiconductor substrate 16. be.

Therefore, in the embodiment shown in FIG. 3(-), the semiconductor substrate 1
6 is provided with a recess lea, and a monitor P is provided within the plane of the recess t6a.
A D4 and a PD 14 for signal reproduction are formed, and beam splitters 17 and 18 are respectively provided thereon.

Further, in the embodiment shown in FIG. 3(b), an auxiliary sub-mount I-16b is provided on the semiconductor substrate 16, and the LD chip 1 is assembled via this auxiliary sub-mount I-16b.
- This is designed to prevent vignetting of the light.

In the above embodiment, an n-type semiconductor substrate 16 was used as the submount, but a p-type semiconductor substrate was used and an n-type diffusion region was formed thereon to form the monitor PD 4 and the signal reproducing PD 171. The same effect can be obtained.

〔Effect of the invention〕

As explained above, in the present invention, a signal regeneration photodiode and a monitor photodiode are formed in the same plane of a submount as a thermal stress relaxation material, and beams are placed on the signal regeneration photodiode and the monitor photodiode, respectively. The beam splitter on the signal reproducing photodiode is installed so as to reflect the incident light in the opposite direction to the signal reproducing photodiode, and the beam splitter on the monitor photodiode reflects the incident light in the opposite direction to the signal reproducing photodiode.・A laser diode chip that is installed so as to be incident on the diode and emits the laser light that is incident on each beam splitter is placed on the plane where the signal reproducing photodiode and the reproducing photodiode are formed on the submount. Or, since it is installed at a required position higher than this plane, the signal reproducing photodiode and the monitoring photodiode are formed on the same board on the same plane, which reduces the number of components required for the pickup, making it smaller and cheaper. . moreover,
In this invention, the signal reproducing photodiode and the monitoring photodiode are formed using photolithography and have high positional accuracy, which has advantages such as requiring less adjustment during pickup assembly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a semiconductor laser device showing an embodiment of the present invention before being assembled into a stem, FIG. 2 is a block diagram of the same before being assembled into a stem, and FIG. 3(a). (b) is a configuration diagram showing another embodiment of the semiconductor laser device of the present invention incorporated in a stem, FIG. 4 is a configuration diagram of a conventional semiconductor laser device, and FIG. 5 is a configuration diagram showing a conventional backup. . In the figure, 1 is an LD chip, 4 is a monitor PD, and 14
is the PD for signal reproduction, and 16 is the submount!・Finding semiconductor substrate, 16a is a recess, tab is an auxiliary sub-mount l
-117 and 18 are beam splitters, and 100 is an LD. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] A signal reproducing photodiode and a monitoring photodiode are formed in the same plane of a submount serving as a thermal stress relaxation material, and a beam splitter is provided on each of the signal reproducing photodiode and the monitoring photodiode, and a beam splitter is provided on each of the signal reproducing photodiode and the monitoring photodiode. The beam splitter on the photodiode is installed so as to reflect the incident light in the opposite direction to the signal reproducing photodiode, and the beam splitter on the monitor photodiode is installed so that the incident light enters the monitor photodiode. Further, a laser diode chip that emits the laser light incident on each beam splitter is placed on the plane where the signal reproducing photodiode and the monitoring photodiode formed on the submount are formed, or at a required position higher than this plane. A semiconductor laser device characterized in that it is installed in.