JP2005228449A - Optical integrated apparatus for optical pickup - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical integrated apparatus for an optical pickup in which a stray light component reflected by a package upper part and a stray light component becoming interference light reflected by a window part side plane of the package are reduced in order to meet the need of miniaturization of the optical integrated apparatus. <P>SOLUTION: The optical integrated apparatus 1 for the optical pickup is provided with a light emitting part 4, a prism 5 having a mirror plane 7 reflecting out-going light from the light emitting part 4 and transmitting the return light, and a light receiving part 6 receiving return light at the lower part of the prism 5. A package 9 provided with a window part 10 through which the out-going light and the return light pass is arranged surrounding the light emitting part 4, the prism 5, and the light receiving part 6, and a taper part 11 is provided at an inner periphery of the window part 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical integrated device for an optical pickup used for recording and reproduction of a media disk such as an optical disk or an optical next-generation disk.

  A laser coupler is used as an optical integrated device 21 for an optical pickup used for recording / reproducing of an optical disk or a magneto-optical disk. As shown in FIG. 3, in the optical integrated device 21, a laser element 24 as a light emitting unit is disposed on a silicon semiconductor substrate 22 via a submount substrate 23, and the laser element 24 is opposed to the laser element 24 on the semiconductor substrate 22. A prism 25 is disposed on the surface of the semiconductor substrate 22 via an adhesive layer (not shown), and a light receiving portion 26 is formed on the surface of the semiconductor substrate 22 immediately below the prism 25. . The prism 25 has a mirror surface 27 that forms, for example, 45 ° that reflects laser light emitted from the laser element 24 and transmits return light reflected by an optical disk (not shown) that is an optical recording medium. The submount substrate 23 is formed of a silicon semiconductor substrate.

  In this optical integrated device 21, the laser light L emitted from the laser element 24 is reflected by the mirror surface 27 of the prism and rises in the vertical direction, and the optical disk passes through a grating, a quarter-wave plate and an objective lens (not shown). Is irradiated. The return light reflected by the optical disc passes through the same optical path, passes through the mirror surface 27 of the prism 25 into the prism 25, and is detected by the light receiving unit 26.

Conventionally, the optical integrated device 21 is packaged so as to cover the laser coupler, and the package 29 is formed with a window portion 30 through which the laser light rising from the mirror surface 27 of the prism 25 is transmitted.
As an optical integrated device, a structure in which the inner surface of the package is roughened is proposed in order to absorb the stray light component reflected by the inner surface of the package of the laser light (see Patent Document 1).
JP 2000-77785 A

  Since the optical integrated device 21 for optical pickup as described above is required to be further downsized, the height h from the semiconductor substrate 28 to the window portion (so-called opening) 30 of the package 29 is also reduced, and accordingly, stray light control is performed. Is getting harder. That is, as shown in FIG. 2A, the laser light L emitted from the laser element 24 passes through the rising window 30 from the reflecting surface 27 of the prism 25, but a part of the laser light L is a flat upper inner wall 29 a of the package 29. The stray light component L1 in which the reflected light L1 reflected by the light becomes a stray light component is directly incident on the light receiving unit 26 and becomes an erroneous signal according to the conditions of the emitted light L, the inner surface height h, and the position of the light receiving unit 26. . Of the reflected light rising vertically from the prism 25, the light reflected by the side surface 31 of the window 30 at the top of the package 29 becomes interference light L2 with respect to the main laser beam. The interference light L2 hits the disk surface, resulting in defocusing. Further, when the return light from the disk is received by the light receiving unit 26 in the prism 25, an erroneous signal is generated.

  In view of the above-described points, the present invention provides an optical pickup for reducing stray light components reflected on the upper part of the package and interference light reflected on the side surfaces of the window of the package as the optical integrated device for the optical pickup is reduced in size. An optical integrated device is provided.

  The optical integrated device of the present invention includes a light emitting unit, a prism having a mirror surface that reflects outgoing light from the light emitting unit and transmits return light, and a light receiving unit that receives the return light below the prism. An integrated device, characterized in that a package that includes a window portion that surrounds a light emitting portion, a prism, and a light receiving portion and that passes through outgoing light and return light is disposed, and a tapered portion is provided on the inner periphery of the window portion. To do.

  As a preferred form of the optical integrated device of the present invention, the tip of the tapered portion is formed so as to be thin enough to remove a component that becomes stray light from the emitted light. The tapered portion is preferably formed so that the angle formed by the inner surface of the tapered portion and the upper inner surface of the package is an obtuse angle smaller than 180 degrees.

  In the optical integrated device of the present invention, the taper provided on the inner periphery of the window portion reduces the reflected light on the side of the window portion of the emitted light rising from the mirror surface of the prism in the package, and the interference light that interferes with the main laser Reduced. Furthermore, by making the tapered portion an obtuse angle smaller than 180 degrees between the tapered portion inner surface and the package upper inner surface, the stray light component due to the reflected light reflected by the package upper inner surface in the vicinity of the window portion of the emitted light is received by the light receiving portion. It is possible to irradiate the inner wall of the package in a direction not to be incident on the package.

  According to the optical integrated device of the present invention, the interference light due to the stray light component reflected on the inner surface of the window portion is reduced, and the stray light component reflected on the upper inner surface near the window portion of the package is not incident on the light receiving portion side. By removing the cause of the erroneous signal at the time of writing, it is possible to take out good outgoing light and provide an optical integrated device with good characteristics.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram showing an embodiment of an optical integrated device according to the present embodiment.
In the optical integrated device 1 according to the present embodiment, a laser element 4 is disposed on a silicon semiconductor substrate 2 via a submount substrate 3, and an adhesive layer (not shown) is formed on the semiconductor substrate 2 so as to face the laser element 4. The prism 5 is disposed through the light receiving portion 6, and a light receiving portion 6 serving as a light detection element for signal detection is formed on the surface of the semiconductor substrate 2 immediately below the prism 5. The light receiving element 6 is formed of a photodiode element. In this case, a photodiode IC is formed on the semiconductor substrate 2 by a plurality of photodiode elements. The prism 5 and the semiconductor substrate 2 are connected by an adhesive layer. The prism 5 has a mirror surface 7 of, for example, 45 ° that reflects the laser light L emitted from the laser element 4 and irradiates the optical recording medium, for example, an optical disk, and transmits the reflected return light. The submount substrate 3 is formed of a silicon semiconductor substrate 2. Further, a signal processing IC for processing a signal detected by the photodiode IC of the light receiving unit 6 is formed on the semiconductor substrate 2.
The semiconductor substrate 2 on which the submount substrate 3, the laser element 4 that is a light emitting unit, and the prism 5 are arranged is arranged on a ceramic base 8 and further packaged by a resin package 9 having an opened window 10.

  And in this Embodiment, the inner edge of the window part 10 provided in the package 9 is formed in a taper shape especially. That is, the tapered portion 11 is provided on the inner periphery of the window portion 10. The tapered portion 11 has a thin end so that light that becomes stray light out of the light rising vertically from the mirror surface 7 can be removed. In this example, the tapered portion 11 protrudes inward toward the semiconductor substrate 2 and has an acute angle θ. Formed. That is, conventionally, interference light generated on the side surface of the window portion is not generated by the tapered portion 11. Further, the tapered portion 11 reflects the reflected light (so-called stray light component) L1 reflected by the tapered inner surface 11a to the package inner wall 9a in a direction not incident on the light receiving portion 6 and the inner surface 11a of the tapered portion 11 and the package 9. The angle α formed with the flat upper inner surface is formed to be an obtuse angle smaller than 180 degrees.

  In this optical integrated device 1, the laser light emitted from the laser element 4 is reflected by the mirror surface 7 of the prism and rises in the vertical direction, and is applied to the optical disc via a grating, a quarter wavelength plate and an objective lens (not shown). The return light that has been irradiated, reflected by the signal recording surface of the optical disc, and passed through the same optical path enters the prism from the prism mirror surface 7 and is detected by the photodiode IC comprising a photodiode element, and the RF signal, that is, the return light from the disc signal surface. Is detected. At the same time, tracking and focus servo signals are detected. The analog signal reproduced in this way is read out. In the case of a DVD, a grating, a hologram, etc. are arranged on the package 9.

Next, the effect | action which the stray light component and interference light of the optical integrated device which concerns on this Embodiment reduce is demonstrated using FIG. 2B.
When the laser beam (dashed line) from the laser element 4 rises vertically on the mirror surface 7 of the prism 5 and passes through the window portion 10, the thickness of the side surface is reduced as much as possible. By having the taper 11 with the sharp tip, the stray light component that has become interference light when hitting the inner peripheral side surface of the conventional window portion is reduced and is not substantially generated. Further, by making the angle formed by the inner surface 11a of the tapered portion 11 and the upper inner surface 9a of the package 9 an obtuse angle smaller than 180 degrees, the reflected light L1 (solid line) irradiated and reflected on the inner surface 11a of the tapered portion 10 is: The package inner wall in a direction not incident on the light receiving unit 6 is irradiated and absorbed. That is, the stray light component L <b> 1 due to the reflected light is not incident on the light receiving unit 6. As described above, in the present embodiment, the tapered portion 11 is thinned and protrudes toward the semiconductor substrate 2 as compared with the conventional case where the window portion indicated by the dotted line has a side surface (see FIG. 2A). By doing so, it is possible to prevent the stray light component L1 directed to the light receiving unit 6 from being generated and the stray light component that has become interference light from hitting the side surface of the window from being generated.

The angle α of the tapered portion can be adjusted so that the reflected light L1 reflected by the inner surface 11a of the tapered portion 11 is irradiated in a direction that does not face the light receiving portion 6.
The reflected light L1 reflected by the tapered portion 11 is absorbed or finely diverged by roughening the inner wall of the package.

  Since the substrate 8 can be formed of ceramic, and the package 9 can be formed of resin, the accuracy in the height direction can be improved, and the stray light component due to the tapered portion 11 can be reduced more accurately. .

  According to the optical integrated device of the present embodiment, by providing an acute taper, stray light components that become interference light reflected by the thickness of the side surface of the window portion can be reduced in the main laser beam, Furthermore, the stray light component due to the reflected light reflected by the package upper inner wall around the window can also be prevented from entering the light receiving unit 6. Therefore, it is possible to reduce erroneous signals when writing to and reading from the optical recording medium.

It is a block diagram concerning one embodiment of an optical integrated device concerning the present invention. It is sectional drawing which shows the principal part of A conventional optical integrated device. B is a cross-sectional view showing the main part of an embodiment of an optical integrated device according to the present invention. It is a block diagram which shows the conventional optical integrated device.

Explanation of symbols

1 .... Optical integrated device, 2 .... Semiconductor substrate, 3 .... Submount substrate, 4 .... Laser element, 5 .... Prism, 6..Light receiving part, 7..Mirror surface, 8..Substrate, 9 .. · Package, 9a · · · Package inner wall, 10 · · Window portion, 11 · · Tapered portion, 11a · · Tapered inner surface, 21 · · Integrated optical device, 22 · · Semiconductor substrate, 23 · · Submount substrate, · · · Laser element, 25..Prism, 26..Light receiving part, 27..Mirror surface, 28..Semiconductor substrate, 29..Package, 29a..Upper inner wall,.

Claims (3)

An optical integrated device comprising: a light emitting unit; a prism having a mirror surface that reflects outgoing light from the light emitting unit and transmits return light; and a light receiving unit that receives the return light below the prism,
A package is provided that surrounds the light emitting unit, the prism, and the light receiving unit, and is provided with a window that passes the emitted light and return light.
An optical integrated device, wherein a tapered portion is provided on an inner periphery of the window portion. The optical integrated device according to claim 1, wherein the tip of the tapered portion is formed to be thin enough to remove a component that becomes stray light from the emitted light. 2. The optical integrated device according to claim 1, wherein the tapered portion is formed such that an angle formed by an inner surface of the tapered portion and an upper inner surface of the package is an obtuse angle smaller than 180 degrees.

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