JPH08213659A - Semiconductor laser device and its manufacture - Google Patents

Abstract

PURPOSE: To provide a semiconductor laser device having a structure capable of preventing the damage of a hologram element at the time of operating the device, and a manufacturing method of it. CONSTITUTION: A semiconductor laser chip 5 or the like is fixed on a block part of the upper surface of a stem 1. A hologram element 10 is fixed in a cap 2 wherein the lower end part is opened and a laser light passing window 3 is arranged on the upper end part, so as to close the passing window 3. The lower end part side of the cap 2 is fixed on the stem 1 so as to accommodate the block part 4. Since the hologram element 10 is fixed in the cap 2 so as to close the passing window 3, a process wherein a window glass is fixed in the passing window 3 and the hologram element 10 is fixed on the upper surface of the stem 1 is cut down.

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 suitable for use in recording / reproducing in an optical disc recording / reproducing apparatus and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 6 is a sectional view of a conventional semiconductor laser device from the front.

In construction, the device comprises a stem 1 and a cap 2, each made of metal. The cap 2 has a cylindrical shape having a lower end opened and a laser beam passage window 3 on the upper end side. A metal block portion 4 is formed on the upper surface of the stem 1. The lower end of the cap 2 is resistance-welded to the upper surface of the stem 1. The block section 4 has a semiconductor laser chip 5, a signal detection photodiode 6, and a PIN photodiode 7 mounted thereon. The semiconductor laser chip 5 emits a laser beam a for recording / reproduction to an optical disc (not shown), and the signal detecting photodiode 6 emits a laser beam b emitted from the semiconductor laser chip 5, reflected by the optical disc and returned. Then, the PIN photodiode 7 monitors the output c of the semiconductor laser chip 5. A window glass 8 is arranged on the inner surface of the laser beam passage window 3 on the upper end side of the cap 2. The window glass 8 is fixed to the inner surface of the upper end portion of the cap 2 with a low melting point glass 9 as an adhesive material adhered to the peripheral portion thereof. Cap 2
On the outer surface of the upper end of the hologram element 10 is a cured resin 11
It is fixed at. The hologram element 10 has a laser beam a from the semiconductor laser chip 5 on its lower surface side, which is divided into three beams d.
A diffraction grating 12 that divides the laser beam d into two parts is provided, and a hologram 13 that polarizes the laser beam d is provided on the upper surface side. A terminal 14 for inputting / outputting an electric signal to / from the semiconductor laser chip 5 and the photodiodes 6 and 7 is attached to the lower surface of the stem 1.

In operation, the semiconductor laser chip 5
In response to the electric signal applied to the terminal 14, the laser light a,
c is the hologram element 10 side and the PIN photodiode 7
It emits to the side and respectively. The laser beam a directed to the hologram element 10 side is split into three beams d by the diffraction grating 12, is polarized by the hologram 13, is condensed by an optical system such as a lens (not shown), and is irradiated onto the optical disc. It The laser beam reflected from the optical disc passes through the optical system to be a beam b polarized by the hologram 13 of the hologram element 10 and then focused on the signal detecting photodiode 6. The signal detecting photodiode 6 outputs an electric signal corresponding to the received laser beam b through the terminal 14. This electric signal is used for recording / reproducing of the optical disc by a circuit device (not shown) of the optical disc recording / reproducing device. The laser light c to the PIN photodiode 7 is converted into an electric signal here for monitoring the output of the semiconductor laser chip and then outputted from the terminal 14.

[0005]

In the above semiconductor laser device, the hologram element 10 is attached to the upper surface of the cap 2 and is exposed to the outside as it is. The corner portion 10a of the hologram element 10 is easily damaged or broken when the device is handled, such as when it is incorporated into an optical pickup. In particular, when a defect occurs in the hologram element 10 when the optical pickup is incorporated, the fragments of the hologram element 10 remain inside the pickup and hinder the transmission of the laser light.

Therefore, it is an object of the present invention to provide a semiconductor laser device having a structure capable of effectively preventing breakage of a hologram element during handling of the device, and a method of manufacturing the same.

[0007]

In order to achieve such an object, in a semiconductor laser device of the present invention, a stem, a block portion formed on the upper surface of the stem, on which at least a semiconductor laser chip is mounted, and a lower end. Part having an opening and a laser beam passage window at the upper end, and the lower end portion fixed on the stem so as to accommodate the block portion, and the cap so as to close the passage window. And a hologram element that is housed and fixed inside. The hologram element is preferably fixed to the inner surface of the cap with a low melting point glass.

Further, in the method for manufacturing the above device of the present invention, a step of mounting a hologram element inside a cap having a lower end opening and a laser light passage window at the upper end so as to close the passage window, , A step of mounting at least a semiconductor laser chip on the block portion of the stem upper surface,
And attaching the lower end of the opening of the cap to the upper surface of the stem.

[0009]

According to the semiconductor laser device of the present invention, since the hologram element is fixed inside the cap, it is effectively protected from damage caused by handling during manufacturing of the device and during transportation. Further, when the hologram element is fixed to the inner surface of the cap with the low-melting glass, the low-melting glass has a property of impervious to water, so that the airtightness inside the cap is improved.

According to the method of manufacturing the above device of the present invention, since the laser beam passage window of the cap is closed by the hologram element, it is not necessary to attach a window glass to the laser beam passage window and the cap is fixed to the stem. After that, it is not necessary to attach the hologram element to the upper surface of the cap, and as a result, the number of steps is reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of a semiconductor laser device according to an embodiment of the present invention as seen from the front, and FIG.
FIG. 4 is a sectional view taken along line AA of FIG. In these figures, the same parts as those in FIG. 6 related to the conventional art are designated by the same reference numerals.

With reference to these figures, the device comprises a stem 1 and a cap 2. The stem 1 is made of metal and has a substantially short cylindrical shape. The cap 2 has a circular laser light passage window 3 having a required diameter on the upper end side and an opening at the lower end, and has a cylindrical shape with an outer diameter slightly smaller than the outer diameter of the stem 1.
A metal block portion 4 having a required height is formed at a position slightly shifted to the right of the center of the upper surface of the stem 1. The lower end side of the cap 2 is fixed to the upper surface of the stem 1 by an appropriate fixing means such as resistance welding so that the block portion 4 is housed inside. The block section 4 has a semiconductor laser chip 5, a signal detection photodiode 6, and a PIN photodiode 7 mounted thereon. With respect to the block portion 4, the semiconductor laser chip 5 is on the upper left side in the figure, the signal detection photodiode 6 is on the upper right side in the figure, and the PIN photodiode 7 is opposed to the semiconductor laser chip 5 in the vertical direction. They are mounted on the lower left side. Since the semiconductor laser chip 5 emits a laser beam a for recording / reproducing to an optical disc (not shown), the signal detecting photodiode 6 is a laser beam b emitted from the semiconductor laser chip 5, reflected by the optical disc and returned. In order to detect the
Are provided to monitor the output light c.

A hologram element 10 is connected and fixed to the inner surface of the upper end of the cap 2 with a low melting point glass 9 so as to close the laser beam passage window 3. This low melting glass 9
Has a property of impermeable to water. Due to this property, in the case of the present embodiment in which the laser beam passage window 3 is closed by the hologram element 10, the hologram element 10 is connected and fixed to the outer surface of the cap 2 with a hardened resin which allows water to easily pass therethrough as in the conventional case, so that the moisture content is reduced. The problem that the laser beam penetrates between the cap 2 and the hologram element 10 and as a result, the transmission of the laser light is hindered is eliminated. Further, the low melting point glass has a higher strength than the cured resin and has sufficient strength even when heated to 400 degrees Celsius.

The hologram element 10 includes a laser beam passage window 3
It has a rectangular shape with a larger outer shape than the above, and a diffraction grating 12 for splitting and generating the laser light a from the semiconductor laser chip 5 into three beams d is provided on the lower surface side, and the laser light d is provided on the upper surface side. Holograms 13 for polarization are provided respectively. A terminal 14 for inputting / outputting an electric signal to / from the semiconductor laser chip 5 and the photodiodes 6 and 7 is attached to the lower surface of the stem 1.

As described above, since the hologram element 10 is attached to the periphery of the laser beam passage window 3 inside the cap 2 so as to close the passage window 3, the hologram element 1 is attached.
0 has the function of a conventional window glass for maintaining airtightness, which eliminates the need for a window glass that has been conventionally required and the hologram element 10 is housed inside the cap 3. In addition to being prevented from being damaged during handling, the damage to the hologram element 10 that occurs when the pickup is incorporated does not hinder the transmission of laser light remaining inside the pickup. further,
Since the hologram element 10 is fixed to the inside of the cap 2 with the low melting point glass 9 and the hardening resin which easily permeates moisture is not used for fixing the hologram element 10, moisture does not enter the optical path of the laser beam and the performance is improved. .

A method of fixing the hologram element 10 inside the cap 2 will be described with reference to FIG. 3. First, as shown in FIG. 3A, a ring shape is formed around the laser light passage window 3 of the cap 2. Then, the solidified low melting point glass 9'is dropped. Then, the hologram element 10 is placed on the low melting point glass 9'as shown in (b). Then, the hologram element 10 is fixed to the periphery of the laser beam passage window 3 of the cap 2 by melting the low melting point glass 9 ′ by heating and then cooling it.

Next, a conventional method of manufacturing a semiconductor laser device and a method of manufacturing a semiconductor laser device according to an embodiment of the present invention will be described, and both methods will be compared and described.

First, referring to FIG. 6, in the conventional manufacturing method, the window glass 8 is fixed to the inner surface of the laser beam passage window 3 of the cap 2 with the low melting point glass 9 in the first step, and the second step is performed. Then, the semiconductor laser chip 5 and the signal detecting photodiode 6 are attached to the block portion 4 on the upper surface of the stem 1, and the PIN photodiode 7 is attached to the upper surface of the stem 1,
The semiconductor laser chip 5 and the photodiodes 6 and 7 are connected to the terminals 14 with metal wires, and the stem 1 is connected in the third step.
The lower end of the cap 2 is resistance-welded to the upper surface of the cap 2 and the hologram element 10 is attached to the upper surface of the cap 2 in the fourth step by the cured resin 1.
Fix at 1. Therefore, at least four steps are required.

On the other hand, referring to FIG. 1, in the method of manufacturing the semiconductor laser device of the present embodiment, the hologram element 10 is provided inside the cap 2 so as to close the laser beam passage window 3 in the first step. In the second step, the semiconductor laser chip 5 and the signal detecting photodiode 6 are attached to the block portion 4 on the upper surface of the stem 1, and the PIN photodiode 7 is attached to the upper surface of the stem 1 in the second step. 6, 7 are connected to the terminals 14 with metal wires, and the lower end of the cap 2 is resistance-welded to the upper surface of the stem 1 in the third step. Therefore, the number of steps is three, and the number of steps can be reduced by one compared with the conventional method. This is the hologram element 10 inside the cap 2.
Since the laser light passage window 3 is closed by the hologram element 10 by attaching the above, it is not necessary to attach a window glass to the laser light passage window 3, and after the cap 2 is fixed to the stem 1, the cap 2 This is because it is not necessary to attach the hologram element 10 to the upper surface, and as a result, only three steps are required. In this way, according to the manufacturing method of the present embodiment, the manufacturing cost can be reduced by reducing the number of steps as compared with the conventional method.

Next, the hologram element 10 and the block portion 4
The adjustment of the distance between the semiconductor laser chip 5 mounted on the substrate and the respective elements of the photodiodes 6 and 7 in the conventional case described with reference to FIG. 4 and in the present embodiment described with reference to FIG. Compare with the case. 4 (a) and 5 (a)
Are views of the cap 2 and the hologram element 10 as viewed from above, and FIGS. 4B and 5B are views of as viewed from the side. Conventionally, as shown in FIG. 4, only the hologram element 10 is monitored for its signal, and adjustment in each of the X and Y directions and rotation adjustment in the θ direction are performed. On the other hand, in this embodiment, as shown in FIG.
The cap 2 itself having the inside is adjusted in each of the X and Y directions and the rotation adjustment in the θ direction in the same manner as described above. Therefore, the adjustment labor is the same in the conventional case and the present embodiment.

[0022]

As described above, according to the semiconductor laser device of the present invention, the stem and the block portion formed on the upper surface of the stem on which at least the semiconductor laser chip is mounted, the lower end portion is opened, and the laser light is emitted at the upper end portion. A cap having a passage window and the lower end side of which is fixed on the stem so as to accommodate the block portion, and a hologram which is accommodated and fixed inside the cap so as to close the passage window. Since it is composed of an element, the corners of the hologram element are not damaged when the apparatus is handled, and the structural reliability of the apparatus is greatly improved.

Further, according to the method of manufacturing a semiconductor laser device of the present invention, the hologram element is attached to the inside of the cap having the opening at the lower end and the passage window for the laser beam at the upper end so as to close the passage window. Since it is a manufacturing method including a step, a step of attaching at least a semiconductor laser chip to the block portion on the upper surface of the stem, and a step of attaching the opening lower end portion of the cap to the upper surface of the stem, a window glass is attached to the passage window of the cap. It is not necessary to fix the hologram element on the upper surface of the cap after fixing the cap or the stem to the stem, and the number of steps can be reduced as compared with the conventional method, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor laser device according to an embodiment of the present invention as seen from the front.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a diagram for explaining a case where a hologram element is attached to a cap.

FIG. 4 is a diagram for explaining a conventional method for manufacturing a semiconductor laser device.

FIG. 5 is a diagram which is used for explaining a method for manufacturing the semiconductor laser device according to the embodiment of the invention.

FIG. 6 is a cross-sectional view of a conventional semiconductor laser device as seen from the front.

[Explanation of symbols]

 1 Stem 2 Cap 3 Laser Light Passing Window 4 Block Section 5 Semiconductor Laser Chip 6 Photodiode for Signal Detection 7 PIN Photodiode 9 Low Melting Glass 10 Hologram Element 12 Diffraction Grating 13 Hologram 14 Terminal

Claims (3)

[Claims] 1. A stem and a block portion formed on an upper surface of the stem, on which at least a semiconductor laser chip is mounted, a lower end portion having an opening and a laser light passage window at an upper end portion, and the block portion is accommodated. As described above, the semiconductor laser comprises: a cap whose lower end portion side is fixed to the upper surface of the stem; and a hologram element which is housed and fixed inside the cap so as to close the passage window. apparatus. 2. The semiconductor laser device according to claim 1, wherein the hologram element is fixed to the inner surface of the cap with a low melting point glass. 3. A step of mounting a hologram element inside a cap having an opening at the lower end and a laser light passage window at the upper end so as to close the passage window, and at least a semiconductor laser chip on the block portion on the upper surface of the stem. A method of manufacturing a semiconductor laser device, comprising: a step of attaching and a step of attaching a lower end portion of the opening of the cap to an upper surface of the stem.