JP2915531B2 - Semiconductor laser device and optical pickup device using this semiconductor laser device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor laser device and an optical pickup device using the semiconductor laser device.

(Prior Art) An optical pickup device irradiates an optical recording medium with light emitted from a light source such as a semiconductor laser, and detects a reflected light that has been reflected and modulated by the optical recording medium with a photodetector. Records and reproduces information.

Since such an optical pickup device requires many optical components such as an objective lens, a semiconductor laser, a beam splitter, and a photodetector, it has conventionally been difficult to reduce the size and weight of the device.

Therefore, in recent years, as shown in FIG. 6, a number of optical pickup devices have been devised that use prisms to reduce the number of components and realize the overall miniaturization. (For example, Japanese Patent Application Laid-Open No. 62-196880)
In addition to forming a semiconductor laser 22 and a photodetector 23,
A prism 24 having, for example, a trapezoidal cross section is fixed on the semiconductor substrate 21 so as to cover the photodetector 23, and an end face 24a of the prism 24 facing the semiconductor laser 22 is provided with a function as a beam splitter. Optical pickup device. The laser light emitted from the semiconductor laser 22 is reflected by the end face 24a of the prism 24, becomes an irradiation beam via the objective lens 25, and enters the optical recording medium 26.
On the other hand, the reflected beam from the optical recording medium 26
25, the light enters the end face 24a of the prism 24,
The light passes through the inside and enters the photodetector 23.

In such an optical pickup device, it is necessary to perform tracking in order to accurately record and reproduce information, but this tracking detects a tracking error signal from optical information detected by a photodetector, and performs tracking. It is general that the objective lens is driven in the tracking direction using an actuator based on the tracking error signal.

Therefore, the conventional optical pickup device is provided with an actuator 27 as a driving means for driving the objective lens in the tracking direction, and supplies a tracking error signal to the actuator 27,
Then, based on this tracking error signal, the objective lens
Drive 25 to correct the tracking error.

(Problems to be Solved by the Invention) As described above, the optical pickup device has been downsized by using the semiconductor laser and the prism. However, even in such a miniaturized pickup device, the tracking operation is performed by driving the objective lens using an actuator. This actuator is used to drive the objective lens,
Therefore, the conventional optical pickup device had a limit in miniaturization. In general, since an actuator is composed of a magnet and a coil, there is a limit in miniaturizing the actuator itself.

Further, in such an optical pickup device, a semiconductor laser device is used as a light source. However, since each semiconductor laser has a variation in a light emitting point, it is troublesome to adjust this variation in a conventional semiconductor laser device. However, it has been difficult to irradiate a laser beam in a desired direction. In addition, when a semiconductor laser is installed on a substrate, high positioning accuracy is required, and there is a disadvantage that positioning takes a long time.

The present invention has been made to solve such a problem, and provides a semiconductor laser device which does not require a high positioning accuracy when installing a semiconductor laser, and uses the semiconductor laser device. It is an object of the present invention to provide an optical pickup device which is reduced in size and weight.

(Means and Actions for Solving the Problems) In order to solve the above problems, a semiconductor laser device according to the first invention of the present application includes a semiconductor laser, a mirror that deflects a light beam emitted from the semiconductor laser, and a semiconductor laser. And a driving unit for driving a mirror to rotate, wherein the mirror and the driving unit are formed on a semiconductor substrate, and the semiconductor laser is disposed on the semiconductor substrate.

As described above, in the semiconductor laser device according to the present invention, the semiconductor laser is disposed on the semiconductor substrate, the mirror that deflects the light beam emitted from the semiconductor laser onto the semiconductor substrate, and the drive that drives the mirror Since the means is formed, even if the emission point of the semiconductor laser varies, the mirror can be rotated to easily change the traveling direction of the light beam, and the variation can be easily corrected.

Further, an optical pickup device according to the second invention of the present application includes a semiconductor laser, a mirror, a driving unit for rotating the mirror, a prism, an objective lens, and a photodetector. The means and the photodetector are formed on a semiconductor substrate, and the semiconductor laser and the prism are irradiated with an optical beam emitted from the semiconductor laser to an optical recording medium via the mirror, the prism and the objective lens, The mirror is arranged on the semiconductor substrate so that a reflected beam from the optical recording medium is incident on the photodetector via the objective lens and the prism, and the mirror is operated by the driving unit based on an output of the photodetector. By rotating the optical recording medium, the light beam irradiated on the optical recording medium is deflected to perform tracking. It is intended to.

Furthermore, the optical pickup device according to the third invention of the present application,
A semiconductor laser, a mirror, a driving unit for rotating and driving the mirror, a prism, an objective lens, and a photodetector, wherein the mirror, the driving unit, and the photodetector are formed on a semiconductor substrate. The semiconductor laser and the prism, a light beam emitted from the semiconductor laser is irradiated to an optical recording medium through the prism, the mirror and the objective lens, the reflected beam from the optical recording medium is the objective lens, The optical recording is performed by arranging on the semiconductor substrate so as to be incident on the photodetector through the mirror and the prism, and rotating the mirror by the driving unit based on an output of the photodetector. The present invention is characterized in that a tracking is performed by deflecting a light beam applied to a medium.

As described above, in the optical pickup devices according to the second and third inventions, the semiconductor laser device according to the first invention is used to further form a photodetector on the semiconductor substrate on which the mirror and its driving means are formed. Since the prism is provided and the mirror is provided with a tracking function, it is only necessary to provide a focusing actuator near the objective lens. Therefore, the mass of the movable part including the objective lens can be reduced, and
It is possible to prevent the objective lens from fluctuating in the tracking direction during high-speed access. Further, the number of components can be further reduced as compared with the conventional device, and the size and weight of the entire device can be reduced.

Embodiment FIG. 1 is a view showing a first embodiment of the optical pickup device of the present invention.

As shown in FIG. 1, a semiconductor substrate 1 has an inclined portion 2, and a semiconductor laser 3 is set on an inclined surface of the inclined portion 2. A mirror 4a and a driving means 4 for rotating and driving the mirror 4a are provided at a position on the semiconductor substrate 1 where the laser beam emitted from the semiconductor laser 3 is irradiated.
Further, a photodetector 5 is formed on the semiconductor substrate 1 at a position where the reflected beam reflected from the optical recording medium is incident. A prism 6 is provided on the photodetector 5, and a semi-transmissive reflection film 6a is formed on an end face of the prism 6 facing the semiconductor laser 3. The laser beam emitted from the semiconductor laser 3 and reflected by the mirror 4a is reflected by the transflective film 6a, guided to the optical recording medium 8 through the objective lens 7, and reflected by the optical recording medium 8. The beam enters the transflective film 6 a via the objective lens 7, passes through the transflective film 6 a, and is guided to the photodetector 5. The objective lens 7 is supported so as to be displaceable in the optical axis direction via support means (not shown), and is driven in the optical axis direction by a focusing actuator (not shown).

A tracking error signal is detected from the optical information detected by the photodetector 5, and the tracking error signal is supplied to the driving means 4 for driving the mirror 4a. The drive means 4 rotates the mirror 4a based on the tracking error signal, deflects the beam incident on the optical recording medium 8, and corrects the tracking error.

FIG. 2 is a perspective view showing the configuration of the mirror 4a and the driving means 4 for rotating this mirror, and FIG. 3 is a cross-sectional view thereof. As shown in FIG. 2, a movable portion 4c is rotatably provided around a rotation shaft 4h provided in parallel with the surface of the semiconductor substrate 1, and a reflective film 4a is formed on the surface of the movable portion 4c to serve as a mirror. Let it work. An electrode 4e is formed on the back surface of the movable part 4c. On the other hand, on the surface of the glass substrate 14 which is located below the movable part 4c and supports the mirror 4a, as shown in FIG. The electrodes 4f and 4g are formed.

Next, the operation of the first embodiment will be described. A voltage based on the tracking error signal is applied to the electrode 4f and the electrode 4e attached to the back surface of the movable section 4c. Electrode 4e,
An electrostatic attraction is generated between the counter electrode 4f and the error 4a, and the error 4a rotates in the direction indicated by the arrow A. On the other hand, when a voltage based on the tracking error signal is applied to the opposite electrode 4g and the electrode 4e in the same manner as described above, the mirror 4a rotates in the direction shown by the arrow B. In this manner, the mirror 4a is rotated, and the traveling direction of the laser beam reflected by the mirror 4a is changed to correct the deviation amount of the irradiation beam after passing through the objective lens 7 from the track on the optical recording medium.

In the configuration of the first embodiment described above, since the position of the laser beam incident on the mirror 4a is always the same, the mirror 4a
Can be reduced, and the driving means 4 can also be reduced in size.

FIG. 4 is a sectional view showing a second embodiment of the optical pickup device of the present invention. This embodiment is different from the first embodiment in that the prism 6 has a trapezoidal cross section.
Instead of 10, the semiconductor substrate 1 has a flat shape without an inclined portion, and the semiconductor laser 3 is provided on the flat surface of the semiconductor substrate 1.

The laser beam emitted from the semiconductor laser 3 is reflected by the semi-transmissive reflection surface 10a of the prism 10, enters the mirror 4a, is further reflected by the mirror 4, and becomes an irradiation beam via the objective lens 7, and becomes an optical beam. The light enters the recording medium 8. The reflected beam reflected by the optical recording medium 8 is
Is reflected by the mirror 4a, and enters the transflective surface 10a. This reflected beam is transflective
The light passes through Oa, enters the prism 10, is refracted on the bottom surface and the surface of the prism 10, enters the photodetector 5, and is detected as optical information.

In the configuration of the second embodiment, the semiconductor substrate 1 has no inclined portion, and the semiconductor laser is installed on a flat surface. Therefore, as compared with the first embodiment in which the semiconductor laser is installed on the inclined surface. The optical path can be easily adjusted.

FIG. 5 is a sectional view showing a manufacturing process of the driving means 4 used in the present invention. The processing of the driving means is performed three-dimensionally by a combination of a thin film forming processing such as CVD and LPE and a selective etching. Such processing methods are, for example, IBM
J.RES.DEVELOP, Vol.24 No.5 `` Silicon Torsional Scab
bubg Mirror ".

As shown in FIG. 5A, a silicon oxide film (SiO ₂ film) 12 is formed on the surface of a silicon substrate 11 by thermal oxidation. Next, as shown in FIG. 5B, a resist mask 13 is attached, and the silicon oxide film 12 around the movable portion 4c is removed by etching using a hydrofluoric acid aqueous solution (FIG. 5C). . The shape of the movable portion 4c is as shown in FIG. 2. The movable portion 4c is connected to the silicon substrate 11 as a rotation axis without removing the central portion in the longitudinal direction of the movable portion 4c. Be supportive. Next, as shown in FIG. 5D, the resist mask 13 is removed, and selective etching is performed using an aqueous potassium hydroxide (KOH) solution to selectively remove the silicon substrate 11 under the movable portion 4a. I do. Next, as shown in FIG. 5 (e), a reflective film 4d is formed on the front surface of the movable portion 4c, and an aluminum electrode 4e is formed on the rear surface by vapor deposition. In the above-described example, the SiO ₂ film 12 is formed on the surface of the silicon substrate 11 by thermal oxidation. However, instead of the SiO ₂ film, a silicon nitride film (Si ₃ N ₄ film) is formed by, for example, a CVD method. It may be formed.

Next, a glass substrate 14 is prepared, and as shown in FIG. 5 (f), after a resist mask 15 is attached to the surface of the glass substrate 14, etching is performed with a hydrofluoric acid aqueous solution to form a concave portion 16. The size of the concave portion 16 is set to be large enough to accommodate the silicon substrate 11 on which the movable portion 4c is formed. Then the mask
15 is removed, and as shown in FIG. 5 (h), two electrodes 4f and 4g are formed on the surface of the concave portion 16 by aluminum evaporation.

The recess 16 in which the electrodes 4f and 4g are formed inside in this way
Next, the silicon substrate 11 on which the movable portion 4c is formed is aligned, and as shown in FIG.
And the glass substrate 14 are bonded by anodic bonding.

FIG. 5 (j) is a perspective view of the mirror 4a and the driving means 4 finally manufactured.

The movable mirror 4a thus formed and the driving means 4
Is installed at a predetermined position on the semiconductor substrate 1 of the optical pickup device described in the first embodiment or the second embodiment.

In the first and second embodiments, the semiconductor substrate 1
Although the driving means 4 is embedded in the
The photodetector 5, the prism 6, and the semiconductor laser 3 may be provided on the silicon substrate 11 by enlarging the silicon substrate 11. In this case, it goes without saying that the semiconductor substrate 1 is unnecessary.

[Effect of the Invention] In the semiconductor laser device of the first invention of the present application, a semiconductor laser is arranged on a semiconductor substrate, and a mirror for deflecting a light beam emitted from the semiconductor laser on the semiconductor substrate, and driving the mirror Since the mirror is rotated to deflect the laser beam, it is possible to easily correct the shift of the light emitting point of the semiconductor laser and to facilitate the positioning of the semiconductor laser with respect to the substrate. .

Further, in the optical pickup device using the semiconductor laser device of the first invention of the present application, since the mirror formed on the substrate has a tracking function, a tracking actuator is not required outside the substrate, and a high-speed access can be achieved. It is possible to prevent the objective lens from fluctuating in the tracking direction, and to reduce the size and weight of the entire apparatus.

Furthermore, when the device of the present invention is applied to a device that performs track servo using a voice coil motor, the device of the present invention is small and light, so that space can be saved and movable Since the mass of the unit can be reduced, high-speed access can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of an optical pickup device of the present invention. FIG. 2 is a perspective view showing an enlarged mirror portion used in the semiconductor laser device and the optical pickup device of the present invention. Is a sectional view of the mirror portion shown in FIG. 2, FIG. 4 is a diagram showing a second embodiment of the optical pickup device of the present invention, FIG. 5 is a mirror shown in FIG. 2 and FIG. FIG. 6 is a cross-sectional view showing a manufacturing process of a portion, and FIG. 6 is a view showing a conventional optical pickup device. DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate 2 ... Spacer 3 ... Semiconductor laser 4 ... Driving means 4a ... Mirror 4c ... Rotating part 4d ... Reflective film, 4e ... Electrode 4f, 4g ... Counter electrode, 4h … Rotating axis 5… Photodetector 6… Prism 6a… Semi-transmissive reflective surface 7… Objective lens 8… Optical recording medium 10… Trapezoidal prism 111… Semiconductor substrate 12… Silicon Oxide film 13: resist mask, 14: glass substrate 15: resist mask, 16: recess

Claims (3)

(57) [Claims] 1. A semiconductor laser comprising: a semiconductor laser; a mirror for deflecting a light beam emitted from the semiconductor laser; and driving means for driving the mirror to rotate; wherein the mirror and the driving means are formed on a semiconductor substrate; A semiconductor laser device, wherein the semiconductor laser is disposed on the semiconductor substrate. 2. A semiconductor laser comprising: a semiconductor laser; a mirror; driving means for driving the mirror to rotate; a prism; an objective lens; and a photodetector, wherein the mirror, the driving means, and the photodetector are formed of a semiconductor. The semiconductor laser and the prism formed on a substrate are irradiated with a light beam emitted from the semiconductor laser through an optical recording medium through the mirror, the prism and the objective lens, and a reflected beam from the optical recording medium Is arranged on the semiconductor substrate so as to be incident on the photodetector through the objective lens and the prism, and the mirror is rotated by the driving means based on an output of the photodetector, whereby An optical pickup device, wherein a tracking is performed by deflecting a light beam applied to an optical recording medium. 3. A semiconductor laser comprising: a semiconductor laser; a mirror; driving means for rotating the mirror; a prism; an objective lens; and a photodetector, wherein the mirror, the driving means, and the photodetector are formed of a semiconductor. The semiconductor laser and the prism formed on a substrate are irradiated with an optical beam emitted from the semiconductor laser to an optical recording medium through the prism, the mirror and the objective lens, and a reflected beam from the optical recording medium Disposed on the semiconductor substrate such that the light enters the photodetector via the objective lens, the mirror, and the prism, and the mirror is rotated by the driving unit based on an output of the photodetector. An optical pickup device configured to deflect a light beam applied to the optical recording medium to perform tracking. .