JP3766780B2 - Semiconductor laser device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor laser device used for an optical disk pickup or the like.
[0002]
[Prior art]
A conventional semiconductor laser device is shown in FIG. As shown in FIG. 3, this semiconductor laser device includes a laser diode (hereinafter referred to as LD) 22 that is a light source for signal reading, and a monitor photodiode (hereinafter referred to as PD) that monitors the intensity of laser light emitted from the LD 22. 23) and a signal receiving PD 24 for converting a reflected light signal including pit information of the optical disk into an electric signal are fixed at predetermined positions on the heat radiation base 21, respectively. The electrodes of the LD 22, the monitor PD 3 and the signal light receiving PD 24 are respectively connected to predetermined leads 30 by wire bonding, and then hermetically sealed by a cap 25, and the laser light is split and refracted on the cap 25. The hologram 26 is fixed. Since the LD 22 and the signal light receiving PD 24 have an attachment error with respect to a predetermined position, the hologram 26 is optically adjusted and fixed at the optimum position so as to compensate for this error.
[0003]
[Problems to be solved by the invention]
FIG. 4 shows a state in which the LD 22, the monitor PD 23 and the signal light receiving PD 24 of the semiconductor laser device are mounted on the heat sink 21. Of the light emitted from the rear end surface of the LD 22, light that does not enter the monitor PD 23 or light that is reflected from the surface of the monitor PD 23 is irregularly reflected in the cap 25 (shown in FIG. 3) and becomes stray light. There is a problem in that this stray light enters the light receiving portion of the signal light receiving PD 24 and becomes noise.
[0004]
FIG. 5 is a cross-sectional view taken along line VV in FIG. 4. The LD 22 is mounted on the heat sink 21 and the monitor PD 23 is mounted on the eyelet 20 (shown in FIG. 3). The distance between the rear end face and the monitor PD 23 is about 3 mm. As shown in FIG. 5, a part of the laser light emitted from the rear end surface of the LD 22 is reflected on the surface of the monitor PD 23, and is emitted into the cap 25 (shown in FIG. 3) to become stray light. Incident light causes noise.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor laser device that can prevent the generation of stray light and reduce noise with a simple configuration.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a semiconductor laser device according to the present invention includes a semiconductor laser, a light receiving element for monitoring light output from the rear end face of the semiconductor laser, and light output from the front end face of the semiconductor laser. In a semiconductor laser device having a signal receiving light receiving element for receiving the reflected light, a light shielding property that covers the optical path so that light does not go out of the optical path between the rear end surface of the semiconductor laser and the monitoring light receiving element A light-shielding portion made of resin is provided, and the interval between the semiconductor laser and the light-receiving element for monitoring is 0.1 mm or more and 2 mm or less. It is formed in the optical path.
[0007]
According to the semiconductor laser device having the above configuration, light emitted from the rear end face of the semiconductor laser that is not received by the monitor light receiving element is blocked by the light shielding portion made of resin. Therefore, the light output of the semiconductor laser does not interfere with the reception of the reflected light reflected by the optical disk or the like. Therefore, generation of stray light can be prevented with a simple configuration, and noise caused by stray light can be reduced.
[0008]
[0009]
[0010]
[0011]
[0012]
[0013]
[0014]
A semiconductor laser device according to an embodiment is characterized in that the light-receiving element for monitoring is mounted on a block provided on a heat radiating table.
[0015]
According to the semiconductor laser device of the above embodiment, by mounting the monitor light receiving element on a block provided on the heat radiating stand, the monitor light receiving element is placed at a position away from the plane of the eyelet to which the heat radiating base is fixed. It is possible to dispose the eyelet so that it does not get in the way during wire bonding of the monitor light receiving element.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The semiconductor laser device of the present invention will be described in detail below with reference to the illustrated embodiments.
[0017]
(First embodiment)
FIG. 1 is a perspective view of an essential part of the semiconductor laser device according to the first embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG.
[0018]
1 and 2, reference numeral 1 denotes a substantially rectangular parallelepiped heat sink having a notch 1a at a corner, 2 denotes an LD as a semiconductor laser fixed on the upper surface of the notch 1a of the heat sink 1, and 3 denotes The monitoring PD 4 as a monitoring light receiving element for monitoring the light output from the rear end face of the LD 2 is a signal receiving PD as a signal receiving light element fixed to the upper surface of the heat radiating table 1. A rectangular block 10 made of metal is fixed to the lower portion of the notch 1a of the heat radiating stand 1 with an epoxy resin or the like, and the monitor PD 3 is fixed on the block 10. In this way, the distance between the rear end surface of the LD 2 and the monitoring PD 3 can be reduced to about 1 mm. The gap between the rear end face of the LD 2 and the monitor PD 3 is easier to cover with a light-shielding resin, which will be described later, but if it is too narrow, the mounting position accuracy of the LD 2 must be increased, so about 0.1 mm to 2 mm. And preferably about 0.5 mm to 1.5 mm.
[0019]
In production, if the distance between the rear end surface of the LD 2 and the monitoring PD 3 is too narrow, the rear end surface of the LD 2 is likely to hit the monitoring PD 3. Is possible.
[0020]
A light shielding portion 5 made of a light shielding resin is formed to cover the space between the rear end surface of the LD 2 and the monitor PD 3. This light-shielding resin is liquid at room temperature and is dropped between the rear end surface of the LD 2 and the monitoring PD 3 by a syringe. If the distance between the rear end face of the LD 2 and the monitoring PD 3 is sufficiently narrow, even if the light shielding resin is dropped, the space 6 surrounded by the light shielding resin is formed.
[0021]
As this light-shielding resin, a UV-curable (or thermosetting) resin having a viscosity that does not enter the gap between the rear end face of the LD 2 and the monitoring PD 3 is selected. Then, it is cured by irradiation (or heating) with UV light. The light shielding resin may be anything as long as it does not transmit the emitted light having a wavelength of 780 nm of the LD2, and for example, a black epoxy resin having thermosetting properties used for exterior of a photocoupler may be used.
[0022]
Further, as the block 10, a laser beam having a length in the emission direction of which the distance between the rear end surface of the LD 2 and the monitoring PD 3 is about 1 mm to 2 mm is used. The angle formed between the light receiving surface of the monitor PD 3 and the optical axis of the laser beam should be slightly inclined from the vertical so that the influence of the return light is reduced. Further, the mounting portion of the block 10 may be cut out so that the center of the monitoring PD 3 is close to the optical axis of the laser light of the LD 2.
[0023]
In the semiconductor laser device having the above configuration, light emitted from the rear end face of the LD 2 that is not received by the monitor PD 3 is scattered and absorbed by the light-shielding resin, so that it does not enter the signal light-receiving PD 4. Therefore, reception of the optical disc signal is not disturbed. Therefore, stray light can be prevented from being generated with a simple configuration, and noise caused by stray light can be reduced.
[0024]
Further, since the monitor PD 3 is close to the rear end face of the LD 2, a sufficient signal output can be obtained even if a monitor PD smaller than the conventional monitor PD is used.
[0025]
In the first embodiment, the block 10 on which the monitor PD 3 is fixed is fixed to the heat radiating base 1 (made of a metal, ceramic, etc. that has good heat dissipation) on which the LD 2 and the signal light receiving PD 4 are fixed. The heat sink and the block may be integrally formed.
[0026]
(Second Embodiment)
The semiconductor laser device according to the second embodiment of the present invention has the same configuration as that of the semiconductor laser device shown in FIGS. 1 and 2 except for the resin portion, and the description of the same components is omitted. FIG. 2 is incorporated.
[0027]
As shown in FIG. 2, after filling the light-transmitting resin between the rear end surface of the LD 2 and the monitoring PD 3, and forming the light-transmitting resin portion 7 so as not to flow by UV irradiation or thermosetting, The translucent resin portion 7 is covered with a light-shielding resin (resin dripping is performed twice). An optical path from the rear end surface of the LD 2 to the monitoring PD 3 is formed by dropping a resin having transparency to the light emitted from the LD 2 between the LD 2 and the monitoring PD 3 to form the translucent resin portion 7. In addition, the light shielding part 5 made of a light shielding resin is formed so as to cover the translucent resin part 7.
[0028]
The translucent resin may be anything such as UV curable resin, epoxy resin, or the like that can transmit the emitted light having a wavelength of 780 nm of LD2, and for example, an elastic silicone rubber resin. However, the translucent resin is low in viscosity and easily enters between the rear end surface of the LD 2 and the monitoring PD 3, and has a high surface tension and does not protrude from between the rear end surface of the LD 2 and the monitoring PD 3. Is the best.
[0029]
In the semiconductor laser device having the above configuration, the laser light emitted from the rear end surface of the LD 2 is partially reflected on the surface of the monitor PD 3 as in the case of the conventional semiconductor laser device, but is blocked by the light-shielding resin 5. Thus, no stray light can be prevented from being emitted into the space in the cap 25.
[0030]
Further, since the light-shielding resin does not enter between the rear end face of the LD 2 and the monitor PD 3 by the light-transmitting resin part 7 filling the optical path, the light-shielding part 5 made of the light-shielding resin surrounding the optical path is surely created. can do.
[0031]
Further, since the distance between the rear end face of the LD 2 and the monitor PD 3 is narrower than in the prior art, even if a translucent resin is dropped into the space between the LD 2 and the monitor PD 3, the translucency is maintained. Supported by the surface tension of the resin, it does not spread around. As a result, a small amount of translucent resin can be used, and it is possible to prevent the translucent resin from adhering to unnecessary portions. The distance between the rear end surface of the LD 2 and the monitor PD 3 is preferably 2 mm or less, and more preferably 1 mm or less. Further, the rear end surface of the LD 2 needs to be separated from the unevenness of the light receiving surface of the monitor PD 3 by 0.1 mm or more.
[0032]
【The invention's effect】
As apparent from the above, according to the semiconductor laser device of the present invention, the semiconductor laser, the monitoring light receiving element for monitoring the light output from the rear end face of the semiconductor laser, and the front end face of the semiconductor laser are provided. In a semiconductor laser device having a light receiving element for receiving light that receives reflected light of light output, a resin that covers the optical path so that light does not go out of the optical path between the rear end face of the semiconductor laser and the light receiving element for monitoring der which the light shielding portion is provided consisting of is, the distance between the semiconductor laser and the monitor light-receiving element and 0.1mm above 2mm or less, the viscosity and spacing of the light-shielding resin, is covered with a light-shielding resin space It is formed in the optical path .
[0033]
Therefore, according to the semiconductor laser device, light emitted from the rear end face of the semiconductor laser that is not received by the light receiving element for monitoring is shielded by the light shielding portion made of resin. Since it does not enter the light receiving element for receiving signal light that receives the reflected light of the light output, stray light can be prevented from being generated with a simple configuration, and noise caused by stray light can be reduced.
[0034]
[0035]
[0036]
In addition, since the monitor light receiving element is mounted on a block provided on the heat radiating stand, the monitor light receiving element can be arranged at a position away from the plane of the eyelet to which the heat radiating base is fixed, and wire bonding of the monitor light receiving element is possible. Sometimes you can keep your eyelets out of the way.
[Brief description of the drawings]
FIG. 1 is a perspective view of an essential part of a semiconductor laser device of a semiconductor laser device according to a first embodiment of the present invention.
FIG. 2 is a sectional view taken along line II-II in FIG.
FIG. 3 is a perspective view showing an entire semiconductor laser device of a conventional semiconductor laser device.
FIG. 4 is a perspective view of a main part of the semiconductor laser device.
FIG. 5 is a cross-sectional view taken along line VV of FIG.
[Explanation of symbols]
1 ... Heat sink,
2 ... LD,
3 ... PD for monitoring,
4 ... PD for signal reception,
5 ... Shading part 6 ... Space,
7: Translucent resin part,
10 ... Block.

Claims (2)

Semiconductor having a semiconductor laser, a light receiving element for monitoring for monitoring the light output from the rear end face of the semiconductor laser, and a light receiving element for signal receiving for receiving reflected light of the light output from the front end face of the semiconductor laser In the laser device,
Providing a light-shielding portion made of a light-shielding resin that covers the optical path so that no light is emitted outside the optical path between the rear end face of the semiconductor laser and the light-receiving element for monitoring;
The interval between the semiconductor laser and the light receiving element for monitoring is 0.1 mm or more and 2 mm or less,
A semiconductor laser device characterized in that a space covered with the light-shielding resin is formed in the optical path by the viscosity of the light-shielding resin and the interval. The semiconductor laser device according to claim 1 ,
A semiconductor laser device, wherein the light-receiving element for monitoring is mounted on a block provided on a heat sink.

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