JP2011216583A - Semiconductor laser device and optical pickup device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a material cost and a manufacturing cost are increased since an antireflection film is formed at a glass plate closing the opening of a cap in a conventional semiconductor laser device.SOLUTION: In a semiconductor laser device 1, the cap 3 is arranged on a stem 2 on a side fixing an LD 10. The opening 4 is formed in a transmission region of a laser beam in the cap 3, and cover glass 5 is arranged so as to close the opening 4. The antireflection film is not formed at the cover glass 5, and the cover glass 5 is abutted against projections 11 and 12 disposed near the opening 4 and inclined and disposed at the internal side face of the cap 4. According to the structure, the semiconductor laser device 1 reducing astigmatism resulting from an astigmatic difference As is achieved in conformity with the return-light countermeasure of the laser beam projected from the LD 10.

Description

  The present invention relates to a semiconductor laser device that realizes a countermeasure against return light by a simple method and an optical pickup device using the same.

  As an example of a conventional semiconductor laser device, a structure shown in FIG. 6 is known. As illustrated, the semiconductor laser device 51 includes, for example, a semiconductor laser chip 52 that emits 660 nm laser light, a case 53, and a cap 54. A part of the cap 54 is located in the laser light emission path from the semiconductor laser chip 52, and an opening 55 is formed in the cap 54 in that region. An exit window 56 made of glass is disposed inside the cap 54 so as to close the opening 55, and antireflection films 57 are formed on both sides of the exit window 56. The antireflection film 57 has, for example, a reflectance of 1.0% with respect to the 660 nm laser light emitted from the semiconductor laser chip 52, and the generation of noise due to the return light is prevented. Is improved (see, for example, Patent Document 1).

  As another example of a conventional semiconductor laser device, a structure shown in FIG. 7 is known. As illustrated, the semiconductor laser device 61 includes a semiconductor laser element 62, a stem 63, and a cap 64. The stem 63 is made of a circular metal plate, and has a thickness of, for example, about 1 to 2 mm. A steel heat dissipating block 65 is fixed to the upper surface of the stem 63. A silicon submount 66 is fixed to the side surface of the block 65, and the semiconductor laser element 62 is fixed to the side surface of the submount 66 by junction down. A monitoring light receiving element 67 for receiving laser light emitted from the lower surface of the semiconductor laser element 62 is fixed to the upper surface of the stem 63.

  A circular window 68 is formed in the cap 64, and a transparent glass plate 69 is disposed inside the cap 64 so as to close the circular window 68. Laser light emitted from the semiconductor laser element 62 is transparent. It passes through the glass plate 69. An antireflection processing region 72 for preventing reflection of the return light of the laser light is disposed on the end surface 71 of the semiconductor laser element 62 provided with the laser emission point 70. The antireflection processing region 72 is roughened by laser processing to prevent the occurrence of noise due to return light (see, for example, Patent Document 2).

Japanese Patent Laying-Open No. 2005-72448 (page 7-8, FIG. 3) Japanese Patent Laid-Open No. 10-107372 (page 2-3, FIG. 1)

  First, in the conventional semiconductor laser device 51 shown in FIG. 6, the semiconductor laser chip 52 is arranged in parallel with the reference plane in the paper plane XZ direction, and the emission direction of the laser light emitted from the semiconductor laser chip 52 is the Z axis on the paper plane. Direction. The emission window 56 arranged in the cap 54 is a plane perpendicular to the laser beam emission direction and is arranged in parallel with the reference plane in the paper plane XY direction. In this structure, part of the laser light reflected by the emission window 56 returns to the light emitting point of the semiconductor laser chip 52, and noise is generated due to the return light of the laser light. For this reason, in the semiconductor laser device 51, as described above, the antireflection film 57 is formed on the emission window 56 to reduce the return light of the laser light and greatly suppress the influence of the return light. However, the formation of the antireflection film 57 on the exit window 56 has a problem that material costs and manufacturing costs increase.

  Next, in the conventional semiconductor laser device 61 shown in FIG. 7, as in the conventional semiconductor laser device 51 shown in FIG. 6, the transparent glass plate 69 is a plane perpendicular to the laser beam emitting direction, It is arranged in parallel with the reference plane in the XY direction. For this reason, as described above, the antireflection processing region 72 is disposed on the end surface 71 of the semiconductor laser element 62 to suppress the influence of the return light. However, it is necessary to perform laser processing on the end surface 71 of the fine semiconductor laser element 62, which increases the manufacturing cost and complicates the manufacturing method.

  In the semiconductor laser device of the present invention, a stem to which a laser diode that emits laser light is fixed, and an upper surface side of the stem to which the laser diode is fixed are formed, and an opening is formed in a region through which the laser light is transmitted. And a pair of protrusions arranged symmetrically with respect to the central axis of the opening on the inner surface side of the cap, the cover glass being disposed so as to close the opening of the cap The cover glass is in contact with the protrusion and is inclined with respect to the inner surface of the cap.

  In the present invention, since the cover glass is disposed to be inclined with respect to the inner side surface of the cap, the return light of the laser light does not enter the light emitting point of the LD, and the generation of noise due to the return light is prevented. .

  Moreover, in this invention, material cost and manufacturing cost are reduced significantly by implement | achieving a return light countermeasure by arrangement | positioning of a cover glass, without forming an antireflection film in a cover glass.

  Moreover, in this invention, it is prevented that a low melting glass flows out on the cover glass by the side of an opening by forming a burr | flash in the peripheral edge part of an opening toward the cover glass side.

  In the present invention, astigmatism due to the astigmatism As is reduced by the arrangement of the cover glass.

  In the present invention, the apparent focal position in the horizontal direction of the laser light is adjusted mainly by the arrangement of the cover glass, and astigmatism due to the astigmatic difference As is reduced.

  Further, in the present invention, by using the semiconductor laser device having the above-described structure, an optical pickup device in which cost is reduced with a simple structure and a countermeasure against returning light is taken is realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a cross-sectional view illustrating a semiconductor laser device of an optical pickup device in an embodiment of the present invention, and FIG. 1A is a plan view, FIG. 1B is a cross-sectional view, and FIG. 1C is a cross-sectional view illustrating a semiconductor laser device of an optical pickup device according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a schematic diagram for explaining laser light of an optical pickup device according to an embodiment of the present invention, and FIG. 3B is a cross-sectional view for explaining a semiconductor laser device. BRIEF DESCRIPTION OF THE DRAWINGS (A) Perspective view and (B) Perspective view for explaining a mounting device for a semiconductor laser device of an optical pickup device in an embodiment of the present invention. It is the schematic explaining the optical system of the optical pick-up apparatus in embodiment of this invention. It is sectional drawing explaining the semiconductor laser apparatus of the optical pick-up apparatus in conventional embodiment. It is sectional drawing explaining the semiconductor laser apparatus of the optical pick-up apparatus in conventional embodiment.

  Hereinafter, a semiconductor laser device and an optical pickup device using the same according to an embodiment of the present invention will be described. In the following description, for example, the paper surface X-axis direction is the lateral width direction (housing width direction) of the semiconductor laser device, the paper surface Y-axis direction is the vertical width direction (housing height direction) of the semiconductor laser device, and the paper surface Z-axis direction. The direction is the height direction of the semiconductor laser device (the depth direction of the housing). The Z-axis direction on the paper surface coincides with the optical axis direction of the optical pickup device, and also coincides with the emission direction of the laser light emitted from the LD.

  First, FIGS. 1A and 1B are cross-sectional views for explaining an embodiment of a semiconductor laser device using a cap of a CAN package.

  FIG. 1A shows a cross section parallel to the reference plane in the YZ direction on the paper surface. The semiconductor laser device 1 is mainly provided on a stem 2 on which an optical semiconductor element such as an LD or a light receiving element is mounted, a cap 3 of a CAN package disposed so as to cover the upper surface of the stem 2, and the cap 3. A cover glass 5 that closes the opening 4 and a lead 6 that is led out from the stem 2.

  The stem 2 is formed by, for example, pressing a metal material such as Fe or Cu into a circular shape and has a thickness of about 1 to 2 mm. A heat radiating block 7 made of a metal material such as Fe or Cu is fixed to the upper surface of the stem 2. Further, as shown by a dotted line, the stem 2 is formed with a through hole 8 penetrating in the thickness direction (Z-axis direction on the paper surface), and the lead 6 is formed in, for example, low melting point glass in the through hole 8. To be fixed.

  The cap 3 is formed by, for example, pressing Kovar, which is an Fe—Ni—Co alloy, into a cylindrical cap shape. As shown in the figure, a circular opening 4 for transmitting laser light is formed on the upper surface of the cap 3, and a cover glass 5 is formed inside the cap 3 so as to close the opening 4, for example, a low melting point. It is fixed with glass. Similarly, the cap 3 is fixed to the upper surface of the stem 2 using low melting point glass. Further, the upper surface side of the stem 2 is hermetically sealed with an inert gas such as nitrogen gas injected by the structure of the cap 3 described above. The cap 3 may be formed of Fe or Fe—Ni alloy.

  Further, as described above, when the cap 3 is pressed, the two protrusions 11 and 12 are formed so as to protrude toward the inner side surface of the cap 3 in the Y-axis direction in the vicinity of the opening 4. The protrusions 11 and 12 are formed so as to have substantially the same height, and the cover glass 5 is disposed so as to contact the protrusions 11 and 12.

  As shown in the drawing, a silicon submount 9 is fixed to the side surface of the heat dissipation block 7, and the LD 10 is fixed to the side surface of the submount 9. The upper surface (side surface on the light emitting point side) of the LD 10 is disposed on the opening 4 side of the cap 3. The side surface of the heat dissipation block 7 and the side surface of the submount 9 are arranged in parallel to the reference plane in the paper surface XZ direction, and the emission direction of the laser light emitted from the LD 10 is the Z axis direction of the paper surface.

  Although not shown, a monitoring light receiving element that receives laser light emitted from the lower surface of the LD 10 is fixed to the upper surface of the stem 2.

  FIG. 1B shows a cross section parallel to the reference plane in the paper plane XZ direction. Although details will be described later, in this cross section, the cover glass 5 is disposed to be inclined with respect to a reference plane (inner side face of the cap 3) in the paper plane XY direction. With this structure, it is possible to take measures against returning light to the LD 10 without forming an antireflection film at least on the cover glass 5 on the LD 10 side. The inclination angle of the cover glass 5 with respect to the reference plane in the paper plane XY direction is adjusted by the height of the protrusions 11 and 12 (see FIG. 1A).

  Next, FIG. 2A is a view from the upper surface side of the semiconductor laser device 1. The cover glass 5 and the protrusions 11 and 12 are arranged on the inner surface side of the cap 3, but are indicated by solid lines.

  As illustrated, the alternate long and short dash line 13 is an axis that passes through the central axis of the semiconductor laser device 1 (the opening 4 of the cap 3) and extends in the X-axis direction on the paper surface, and the alternate long and two short dashes line 14 indicates the semiconductor laser device 1. This is an axis that passes through the central axis of the (opening 4 of the cap 3) and extends in the Y-axis direction on the paper surface. A point that intersects with the alternate long and short dash line 13 and the two-dot chain line 14 and is indicated by a cross 15 is the central axis of the semiconductor laser device 1 (the opening 4 of the cap 3). The LD 10 is fixed on the submount 9 so that the light emitting point of the LD 10 is located on the central axis indicated by the x mark 15. Further, the protrusions 11 and 12 are in the vicinity of the opening 4 of the cap 3, and are arranged symmetrically with respect to the central axis on the paper surface X-axis indicated by a one-dot chain line 13.

  The cover glass 5 is processed into a quadrilateral shape, one side surface 18a of the cover glass 5 is arranged in parallel to the reference plane in the paper surface YZ direction, and one side surface 18b of the cover glass 5 is a reference material in the paper surface XZ direction. Arranged parallel to the surface.

  FIG. 2B is a cross-sectional view taken along the two-dot chain line 14, and the protrusions 11 and 12 are formed by pressing from the arrow 16 side, and the heights T1 of the protrusions 11 and 12 are substantially the same. It becomes. The cover glass 5 is fixed by a low melting point glass 17 indicated by sand-like hatching so as to come into contact with the protrusions 11 and 12. On the other hand, FIG. 2C is a cross-sectional view taken along the alternate long and short dash line 13, and the end of one side 18 a of the cover glass 5 abuts on the inner side of the cap 3 as indicated by a circle 19. In this way, it is fixed by the low melting point glass 17. With this structure, the cover glass 5 is fixed to the inner surface of the cap 3 at at least three locations and fixed in a stable state. The inclination angle of the cover glass 5 with respect to the reference plane (inner side surface of the cap 3) in the paper XY direction is adjusted according to the height T1 of the projections 11 and 12 with the end portion of the one side 18a as the rotation axis. The

  2B and 2C, the opening 4 of the cap 3 is formed by punching the cap 3 from the arrow 16 side. Therefore, an annular burr is formed around the opening 4 toward the inner surface of the cap 3 as indicated by a circle 20. As described above, the cover glass 5 is fixed in position using the three portions such as the projections 11 and 12 of the cap 3, and then the low melting point glass 17 is placed between the cover glass 5 and the inner surface of the cap 3. Let it flow. Thereafter, the cap 3 is placed in a heating furnace and heated to a temperature at which the low melting point glass 17 is melted, whereby the opening 4 side of the cap 3 is sealed. At this time, the melted low melting point glass 17 spreads between the cover glass 5 and the inner surface of the cap 3, but inside the opening 4, the melted low melting point glass 17 is cap 3 due to its surface tension. The tip of the burr and the cover glass 5 are connected. The melted low melting point glass 17 is prevented from flowing out toward the opening 4 due to the burr, and the low melting point glass 17 is fixed between the cover glass 5 and the cap 3 in a fixed shape. The space between the cover glass 5 and the inner side surface of the cap 3 is sealed with the low-melting glass 17, particularly when an LD having a blue-violet (blue) wavelength band of 400 nm to 420 nm (for example, 405 nm) is used. This solves the problem that suspended matter in the air such as dust accumulates at the light emitting point of the LD and the output decreases.

  As shown in FIG. 2A, the upper surface of the opening 4 and the cap 3 is circular, but the cover glass 5 processed into a quadrilateral shape is used. The cover glass 5 is formed by the steps described below. First, for example, a large glass plate made of borosilicate glass is prepared, and the glass plate is scribed in the shape of the cover glass 5 using, for example, a diamond cutter having a high penetration blade. At this time, in the scribe operation, a notch is formed in the thickness direction of the glass plate, and a vertical crack is formed in the thickness direction. Then, it is divided | segmented into each cover glass 5 by applying a press to a glass plate from the scribe side by a worker's manual work. That is, by making the shape of the cover glass a quadrilateral shape, the workability is greatly improved as compared with the case of a conventional circular or hexagonal shape.

  FIG. 3A is a schematic diagram illustrating the intensity distribution of laser light emitted from a general LD. The LD has an active layer that emits laser light, and the laser light emitted from the LD is distributed in the horizontal direction in the horizontal direction with respect to the active layer and in the vertical direction with respect to the active layer. And a vertical laser beam. As shown in the figure, the apparent focal point of the horizontal laser beam is x, the apparent focal point of the vertical laser beam is y, and the focal point x is located in the depth direction of the LD from the focal point y. . The difference in position between the focal point x and the focal point y is called astigmatism difference As. Usually, the spread angle θ1 of the laser beam in the vertical direction is larger than the spread angle θ2 of the horizontal laser beam, and the intensity distribution of the laser beam has an elliptical distribution that spreads greatly in the Y-axis direction. ing.

  As shown in FIG. 3B, first, since the anti-reflection film is not formed on the cover glass 5, a part of the laser light emitted from the LD 10 is directed to the LD 10 side as indicated by the solid line 21. And reflected. At this time, since the cover glass 5 is disposed at an inclination, the reflected return light travels to a region away from the light emitting point of the LD 10, and the laser light emitted from the LD 10 interferes with the return light. Is prevented. As a result, the generation of noise due to the return light of the laser beam is prevented, the FFP (Far-Field Pattern) waveform is not significantly disturbed, and the light condensing property to the optical information recording medium is improved. Then, data writing to the optical information recording medium and data reading from the optical information recording medium are performed with high accuracy. Moreover, since it is not necessary to form an antireflection film on the cover glass 5 as described above, material costs and manufacturing costs are greatly reduced.

  Next, for example, the LD 10 is mounted on the submount so that the horizontal laser beam described above with reference to FIG. 3A matches the X-axis direction of the paper surface and the vertical laser beam matches the Y-axis direction of the paper surface. 9 is fixed on the side surface. Therefore, the intensity distribution of the laser light emitted from the LD 10 has an elliptical distribution that spreads greatly in the Y-axis direction on the paper surface. In order to reduce the astigmatism due to the astigmatism As, in this embodiment, astigmatism in the opposite direction to the astigmatism due to the astigmatism As is generated. That is, by arranging the cover glass so as to be inclined with respect to the above-described horizontal laser light, the apparent focal point x in the horizontal direction approaches the apparent focal point y in the vertical direction, which is caused by the astigmatism As. Astigmatism is reduced. Specifically, the LD 10 that emits a laser beam having a blue-violet (blue) wavelength band of 405 nm is used, the astigmatism As of the LD 10 is 2 to 3 μm, the thickness of the cover glass 5 is 0.25 μm, When the refractive index is 1.52, in the horizontal direction of the laser light, the cover glass 5 is inclined about 10 degrees toward the LD 10 side with respect to the reference plane in the paper XY direction (a plane perpendicular to the optical axis). By arranging, the astigmatism due to the astigmatism As is corrected in a direction that greatly cancels out. In other words, in the present embodiment, the astigmatism As is adjusted in accordance with the countermeasure against the return light of the laser light emitted from the LD 10 by arranging the cover glass 5 tilted in the direction of adjusting the horizontal laser light. Astigmatism due to the is reduced.

  Next, FIG. 4A illustrates the LD holder 22 to which the semiconductor laser device 1 described above is attached. The LD holder 22 has a rectangular parallelepiped shape, and the side surfaces 23 and 24 serve as reference planes in the XY direction with respect to the optical axis direction and are perpendicular to the optical axis direction. Further, the side surfaces 25 and 26 become reference planes in the YZ direction with respect to the optical axis direction, and the side surfaces 27 and 28 become reference planes in the XZ direction with respect to the optical axis. A through hole 29 having the same shape as the semiconductor laser device 1 is formed in the LD holder 22 so as to penetrate the opposing side surfaces 23 and 24, and the position of the semiconductor laser device 1 is fixed in the through hole 29. A seating surface 30 is formed. The seat surface 30 serves as a reference surface in the XY direction parallel to the side surfaces 23 and 24.

  Next, FIG. 4B illustrates the housing 31 to which the LD holder 22 is attached. In the attachment region of the LD holder 22 of the housing 31, for example, a recess 32 that matches the shape of the LD holder 22 is formed. The side surface 33 in the recess 32 serves as a reference surface in the XY direction with respect to the optical axis direction, and the side surface 34 serves as a reference surface in the YZ direction with respect to the optical axis direction. An opening 35 is formed on the side surface 33 in alignment with the through hole 29 of the LD holder 22, and the center axis of the opening 35 coincides with the optical axis direction of the optical pickup device as indicated by a three-dot chain line. Then, the laser light emitted from the LD holder 22 travels on the optical axis indicated by a three-dot chain line through the opening 35.

  Here, a method of attaching the LD holder 22 to the housing 31 will be described. First, the side surface 23 of the LD holder 22 and the side surface 33 of the housing 30 are brought into contact with each other, and the vertical surface (reference surface in the XY direction) is fixed with respect to the optical axis direction of the optical pickup device. At this time, the side surface 28 of the LD holder 22 abuts on the housing 31, and the reference surface in the XZ direction is also fixed. Next, the LD holder 22 is moved horizontally in the X-axis direction, the side surface 26 of the LD holder 22 and the side surface 34 of the housing 31 are brought into contact with each other, and the reference surface in the YZ direction is fixed. Thereafter, the LD holder 22 is fixed to the housing 31 by press-fitting the LD holder 22 into the housing 31 so as to horizontally move the LD holder 22 in the Z-axis direction.

  As described above, when the semiconductor laser device 1 is attached to the LD holder 22 and when the LD holder 22 is attached to the housing, the reference plane in the XY direction, the reference plane in the XZ direction, and the reference plane in the YZ direction are considered. Thus, astigmatism due to the astigmatism As is reduced in accordance with the countermeasure against the return light of the laser light emitted from the LD 10.

  Finally, the optical system of the optical pickup device will be described with reference to FIG. The illustrated three-dot chain line indicates the optical axis of the optical pickup device, and the optical system components described below are arranged with high positional accuracy with respect to the optical axis.

  The first semiconductor laser device 36A emits laser light having a first wavelength (blue-violet (blue) wavelength band 400 nm to 420 nm (for example, 405 nm)). The second semiconductor laser device 36B emits laser light having a second wavelength (red wavelength band 645 nm to 675 nm (for example, 655 nm)) and laser light having a third wavelength (infrared wavelength band 765 nm to 805 nm (for example, 785 nm)). To do. The structures of the semiconductor laser devices 36A and 36B are the same as the structure of the semiconductor laser device 1 described above.

  The first diffraction grating 37 is disposed between the first semiconductor laser device 36A and the polarization beam splitter 38, and laser light emitted from the first semiconductor laser device 36A is incident thereon. The first diffraction grating 37 includes a diffraction grating that separates incident laser light into 0th-order light, + 1st-order diffracted light, and −1st-order diffracted light, and S-polarized light with respect to the polarization plane of the polarization beam splitter 38. And a half-wave plate that converts the light into linearly polarized light. Similarly, the second diffraction grating 39 is disposed between the second semiconductor laser device 36B and the polarization beam splitter 38, and includes a diffraction grating and a half-wave plate. The second diffraction grating 39 converts incident laser light into P-polarized linearly polarized light with respect to the polarization plane of the polarization beam splitter 38.

  The coupling lens 40 is disposed between the second diffraction grating 39 and the polarization beam splitter 38, and converts the divergence angle of the incident laser light. As illustrated, by using the coupling lens 40, the collimating lens 42 and the objective lens 44 can be shared for a plurality of laser beams. The polarization beam splitter 38 reflects the S-polarized laser light incident from the first diffraction grating 37 and transmits the P-polarized laser light incident from the coupling lens 40.

  The half mirror 41 reflects the S-polarized laser light incident after being reflected by the polarizing beam splitter 38 and the P-polarized laser light incident through the polarizing beam splitter 38 in the direction of the collimating lens 42. Further, the half mirror 41 transmits the return light of the laser light incident from the collimator lens 42. The collimating lens 42 converts the laser light incident from the half mirror 41 into parallel light. The parallel light of the laser beam converted by the collimator lens 42 enters the quarter wavelength plate 43.

  The quarter wavelength plate 43 converts the laser light incident from the collimator lens 42 from linearly polarized light to circularly polarized light. The quarter-wave plate 43 converts the return light of the laser light incident from the objective lens 44 from circularly polarized light to linearly polarized light. The objective lens 44 condenses the laser light incident from the quarter wavelength plate 43 on the signal recording layer of the optical information recording medium 45 to which the objective lens 44 corresponds.

  The return light of the laser beam reflected by the optical information recording medium 45 is converted into parallel light by the objective lens 44 and is incident on the quarter wavelength plate 43, and from the circularly polarized light to the linearly polarized light by the quarter wavelength plate 43. Converted. Then, the return light of the laser light that has become linearly polarized light passes through the collimator lens 42, passes through the half mirror 41, and enters the detection lens 46.

  The detection lens 46 condenses the return light of the laser light on the photodetector 47 and generates astigmatism in the return light of the laser light to generate a focus error signal. And the photodetector 47 photoelectrically converts the return light of the received laser beam.

  By using the semiconductor laser device 1 including the cap 3 to which the cover glass 5 is fixed as described above, a countermeasure for returning light of the LD 10 is taken with a simple structure, and data writing to the optical information recording medium or from the optical information recording medium is performed. Thus, an optical pickup device that can accurately read the data is realized.

  In the present embodiment, the cover glass 5 has three portions, that is, the protrusions 11 and 12 and the end portion of the one side 18a of the cover glass 5 with respect to the reference plane (the inner surface of the cap 3) in the paper plane XY direction. In the above description, the inclination angle of the cover glass 5 with respect to the reference plane in the paper plane XY direction is adjusted by the height of the protrusions 11 and 12, but the present invention is not limited to this case. For example, as shown in FIG. 2 (A), a protrusion is formed on the alternate long and short dash line 13 in the vicinity of the opening 4, and the cover glass 5 is fixed at three positions of the new protrusion and the protrusions 11 and 12. Even if it is good. In this case, the inclination angle of the cover glass 5 with respect to the reference plane in the paper XY direction is adjusted by adjusting the height of the new protrusion. Further, since the two-dot chain line 14 in which the protrusions 11 and 12 are arranged serves as a rotation axis, the cover glass 5 is also tilted in a certain direction, so that astigmatism due to the astigmatism As is more efficiently caused. Reduced. In addition, various modifications can be made without departing from the scope of the present invention.

1 Semiconductor Laser Device 3 Cap 4 Opening 5 Cover Glass 10 LD
11, 12 Protrusions 17 Low melting point glass 22 LD holder 31 Housing

Claims (6)

A stem to which a laser diode emitting laser light is fixed;
A cap disposed on the upper surface side of the stem to which the laser diode is fixed, and an opening formed in a region through which the laser light is transmitted;
A cover glass arranged to close the opening of the cap;
A pair of protrusions disposed symmetrically with respect to the central axis of the opening is formed on the inner surface side of the cap, the cover glass abuts on the protrusion, and the inner surface of the cap A semiconductor laser device, wherein the semiconductor laser device is tilted. 2. The semiconductor laser device according to claim 1, wherein an antireflection film is not formed on the cover glass. The opening is formed by punching the cap to the inner surface side, and a burr is disposed on the inner surface side at the peripheral end of the opening,
3. The semiconductor laser device according to claim 2, wherein the low melting point glass for fixing the cover glass and the cap is formed on the opening side so as to connect the burr and the cover glass. The central axis of the opening coincides with the optical axis of the laser beam, the inner surface of the cap is a plane perpendicular to the optical axis, and the pair of protrusions are parallel to the vertical direction of the laser beam. The semiconductor laser device according to claim 2, wherein the semiconductor laser device is arranged so as to be The cover glass has a four-sided shape, and one side surface of the cover glass is arranged to be parallel to the vertical direction of the laser light,
An end portion of one side edge of the cover glass is in contact with an inner surface of the cap, and the cover glass is inclined with respect to an inner surface surface of the cap with the end portion of the one side edge as a rotation axis. The semiconductor laser device according to claim 4. In an optical pickup device that writes data to an optical information recording medium or reads data from the optical information recording medium by laser light emitted from at least a semiconductor laser device,
6. The optical pickup device according to claim 1, wherein the semiconductor laser device is the semiconductor laser device according to any one of claims 1 to 5.

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