JP2003132583A - Semiconductor laser and optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the amount of the light outputted by a semiconductor laser chip without almost losing it. SOLUTION: The semiconductor laser 21 has a semiconductor laser chip 23, an optical wavelength divider 27, a first optical element 28, a second optical element 29, and an optical detector 30. The optical wavelength divider 28 has a beam splitter 25 and a reflection mirror 26. The light outputted by the semiconductor laser chip 23 is partly reflected by the beam splitter 25 but mostly received by a monitor optical detector 36. Since the light reflected by the optical recording medium 24 is reflected or diffracted by the beam splitter 25, the reflection mirror 26, and the second optical element 29, and received by the optical detector 30, the semiconductor laser chip 23 is not affected by the light reflected on the optical recording medium. Thus, the amount of the light is not lost almost all, and the output control can be correctly carried out for the semiconductor laser chip.

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 and an optical pickup device for recording or reproducing information on an optical recording medium.

[0002]

2. Description of the Related Art As an optical recording medium capable of recording or reproducing information, a CD (Compact Disc) in which information is recorded or reproduced by light having a wavelength of 780 nm is widely used. Recently, DVDs (Digital Versatile Discs) capable of recording more information than CDs have been used with the increase in storage capacity of optical recording media. Information is recorded or reproduced on a DVD by light having a wavelength of 630 to 690 nm, which is shorter than the wavelength used for a CD.

Since the optical recording medium has a strong wavelength dependency on the light reflectance and the recording capacity of information, the wavelength of the light different from the wavelength of the light used for recording or reproducing information on one optical recording medium. When light is used, there is a problem that information cannot be reproduced or recorded on the one optical recording medium. Therefore, in order to be able to use both an optical recording medium having a small recording capacity and an optical recording medium having a large recording capacity, it is possible to reproduce or record information on two types of optical recording media. A semiconductor laser device and an optical pickup device including the same are required. Further, in order to maintain stable recording or reproducing operation of the semiconductor laser device and the optical pickup device with respect to the optical recording medium, when used for both the optical recording medium having a small storage capacity and the optical recording medium having a large storage capacity. It is necessary to keep the output of the semiconductor laser chip corresponding to each optical recording medium constant.

FIG. 11 is a system diagram showing a simplified configuration of the conventional optical pickup device 1. The optical pickup device 1 includes first and second semiconductor laser chips 2 and 3 which emit lights having different wavelengths. The light emitted from the first semiconductor laser chip 2 is diffracted by the tracking beam generating diffraction grating 4 into first-order diffracted light, zero-order diffracted light, and −1st-order diffracted light, and then most of the light is diverged by the first beam splitter 5. The remaining light is reflected in the direction of the rising mirror 6, passes through the first beam splitter 5, and is received by a photodiode 7 which is a light detecting means for laser output monitoring. The light incident on the rising mirror 6 is bent by 90 degrees and guided in a direction toward the optical recording medium 8, collimated by the collimator lens 9, and condensed on the optical recording medium 8 by the objective lens 10. . The optical output of the first semiconductor laser chip 2 detected by the photodiode 7 is an APC (Automatic Power Controller) which is a system controller including a CPU (Central Processing Unit) not shown.
ol). The APC keeps the output of the first semiconductor laser chip 2 constant by controlling the drive current of the first semiconductor laser chip 2 in response to the light detection output of the photodiode 7.

The light emitted from the second semiconductor laser chip 3 is reflected by the second beam splitter 11 to produce the first light.
The light is bent 90 degrees in the direction of the beam splitter 5, and is divided into light transmitted by the first beam splitter 5 in the direction of the rising mirror 6 and light reflected by the first beam splitter 5 and bent 90 degrees and received by the photodiode 7. Similar to the output of the first semiconductor laser chip 2, the output of the second semiconductor laser chip 3 is kept constant in response to the light detection output of the photodiode 7.

The light reflected by the optical recording medium 8 passes through the objective lens 10, is collimated again by the collimating lens 9, is bent 90 degrees by the rising mirror 6, and is divided into first and second beam splitters 5, 11. After passing through, the light is focused by the condenser lens 12, and then received by the photodetector 13. A detection signal, for example, a tracking servo signal is obtained based on the amount of light received by the light detection means 13.

Further, Japanese Patent No. 3089200 discloses a conventional technique for keeping the optical output of a semiconductor laser chip constant when one type of wavelength is used for a light source.

FIG. 12 is a schematic sectional view showing a simplified structure of another conventional optical pickup device 14.
Semiconductor laser device 15 provided in the optical pickup device 14.
Includes a hologram element 16. The light emitted from the third semiconductor laser chip 17 is diffracted by the hologram element 16 into first-order diffracted light, zero-order diffracted light, and −1st-order diffracted light, and the first-order diffracted light is provided for the laser output monitor provided in the housing 18 of the optical pickup device 14. The light is received by the photodiode 7 which is the light detecting means. The detected light output is AP
The APC is input to C and responds to the photodetection output by the photodiode 7, and controls the drive current of the third semiconductor laser chip 17, whereby the third semiconductor laser chip 1
Keep the output of 7 constant.

Further, when reproducing information from an optical recording medium using a low output semiconductor laser chip, the following technique different from the above-mentioned conventional technique is used.
The light emitted from the semiconductor laser chip in the direction opposite to the direction of the light emitted toward the optical recording medium is received by the photodiode provided in the semiconductor laser device, and the light detection output by this photodiode is input to the APC. To do. The APC responds to the light detection output and controls the output of the semiconductor laser chip to be constant.

[0010]

The above-described conventional optical pickup device 1 and another conventional optical pickup device 14 have the following problems.

The conventional optical pickup device 1 is provided with first and second semiconductor laser chips 2 and 3 for emitting lights having different wavelengths as light sources, and the first and second beam splitters 5 and 11 are provided for the respective light sources. Since each of them is provided, there is a problem that the storage space for the optical member is increased, the size of the device is increased and the cost of the device is increased due to an increase in the number of members.

In another conventional optical pickup device 14, the light emitted from the third semiconductor laser chip 17 is first-order diffracted light by the hologram element 16.
Since the light is diffracted into the zero-order diffracted light and the minus first-order diffracted light, the light amount of the zero-order diffracted light condensed on the optical recording medium 8 varies depending on the diffraction efficiency of the hologram element 16, but the light amount of the emitted light before diffraction differs. To 50 to 80%. After the reflected light from the optical recording medium 8 is further diffracted by the hologram element 16, the amount of light received by the photodiode 7 is 8 to the amount of reflected light at the time of being reflected by the optical recording medium 8. Reduced to 20%. Such a decrease in the amount of light has a problem of reducing the speed of recording information on the optical recording medium 8.

In addition, CD-R (Recordable) / RW (Re
writable) and DVD-R / RW, in an optical pickup device equipped with a high-power semiconductor laser device for recording information on an optical recording medium, the light emitted from the semiconductor laser chip of the semiconductor laser device has high intensity. When the light focused on the optical recording medium and reflected from the optical recording medium reaches the semiconductor laser chip again, the intensity of the reflected light is high. An instability occurs and a scoop phenomenon occurs in which the output of the semiconductor laser chip fluctuates. Therefore, a technique for stabilizing the output of a semiconductor laser chip used in a low-output semiconductor laser device, that is, a photodiode provided in the semiconductor laser device is provided in a direction opposite to the direction from the semiconductor laser chip toward the optical recording medium. The technique of receiving the emitted light and controlling the output of the semiconductor laser chip without reducing the light amount of the light used for reproducing information cannot be used for a high-output semiconductor laser device. Therefore, in an optical pickup device equipped with a high-power semiconductor laser device, there is a problem that the output of the semiconductor laser chip must be controlled by utilizing the light emitted toward the optical recording medium.

It is an object of the present invention to provide a semiconductor laser device and an optical pickup device which can perform output control with almost no reduction in the amount of emitted light and can realize miniaturization. .

[0015]

SUMMARY OF THE INVENTION The present invention provides a semiconductor laser device which emits light toward an optical recording medium on which information is recorded or reproduced by light and receives reflected light from the optical recording medium. A wavelength including a semiconductor laser chip that emits light, a beam splitter that transmits and / or reflects light emitted from the semiconductor laser chip and reflected light from the optical recording medium, and a reflection mirror that further reflects the light reflected by the beam splitter. A first optical element disposed between the semiconductor laser chip and the wavelength separating optical element for separating light, and diffracting light emitted from the semiconductor laser chip.
An optical element, a second optical element which is arranged closer to the semiconductor laser chip than the wavelength separating optical element, and which diffracts the light reflected by the reflection mirror of the wavelength separating optical element, and a light which is diffracted by the second optical element. A semiconductor laser device including a light detecting unit for receiving light.

According to the invention, the light emitted from the semiconductor laser chip is diffracted by the first optical element,
Part of the light is reflected by the beam splitter, and the remaining light is transmitted toward the optical recording medium. Part of the light reflected by the beam splitter is used to control the output of the semiconductor laser chip described later. The reflected light from the optical recording medium is reflected by the beam splitter toward the reflecting mirror, further reflected toward the second optical element by the reflecting mirror, and diffracted by the second optical element. The diffracted light is received by the light detection means, and detects the information and the detection signal such as the tracking error signal provided in the optical recording medium. As a result, the semiconductor laser chip is not affected by the reflected light from the optical recording medium. Therefore, the output of the semiconductor laser chip can be accurately controlled by using a part of the light emitted from the semiconductor laser chip. You can Further, since the light emitted from the semiconductor laser chip to the optical recording medium is transmitted and diffracted by only one optical element, the light can be emitted to the optical recording medium without substantially reducing the light amount of the emitted light.

The present invention further includes a third optical element which is arranged between the second optical element and the wavelength separating optical element and which diffracts the light reflected by the reflection mirror. The light is diffracted by the third optical element and the light diffracted by the second optical element is received.

According to the present invention, by providing the two second and third optical elements, it is possible to correspond to the semiconductor laser chips respectively emitting two kinds of light having different wavelengths, and the light from each semiconductor laser chip is desired. Can be diffracted in each direction. The light detecting means is provided so as to receive the light diffracted by the two optical elements. This makes it possible to record or reproduce information on two different types of optical recording media by using two semiconductor laser chips that respectively emit light of different wavelengths.

The present invention further includes a fourth optical element which is arranged between the wavelength separating optical element and the first optical element and which diffracts the light transmitted by the beam splitter. The light diffracted by the fourth optical element and the light diffracted by the second optical element are received.

According to the present invention, by providing the two second and fourth optical elements similarly to the above-mentioned second invention, it is possible to correspond to the semiconductor laser chip which respectively emits two kinds of light having different wavelengths. The light emitted from each semiconductor laser chip can be diffracted in a desired direction.
The light detecting means is provided so as to receive the light diffracted by the two optical elements. This makes it possible to record or reproduce information on two different types of optical recording media by using two semiconductor laser chips that respectively emit light of different wavelengths.

The present invention is also characterized in that the second optical element and the fourth optical element are provided in the same plane orthogonal to the axis of the light emitted from the semiconductor laser chip.

According to the present invention, since the second optical element and the fourth optical element are provided in the same plane, the size of the semiconductor laser device can be reduced without causing a problem of the space for installing the optical members. Can be realized.

According to the present invention, the beam splitter is
It is a polarizing beam splitter.

According to the invention, the beam splitter is a polarizing beam splitter. Therefore, by selecting the polarization beam splitter so as to transmit the light of the main polarization direction of the emitted laser light and reflect the part of the light mixed with the laser light and having the polarization direction different from the main polarization direction. The output of the semiconductor laser chip can be controlled with almost no reduction in the amount of light focused on the optical recording medium.

The present invention further comprises a condensing means provided with the semiconductor laser device, arranged between the semiconductor laser device and the optical recording medium to condense light emitted from the semiconductor laser device onto the optical recording medium. An optical pickup device, comprising: a monitor light detection unit that receives light reflected by a beam splitter included in the semiconductor laser device and monitors the output of the semiconductor laser chip.

According to the present invention, the semiconductor laser device included in the optical pickup device has almost no decrease in the amount of light emitted to the optical recording medium and is excellent in light output stability.
Therefore, the optical pickup device can record or reproduce information on the optical recording medium and perform various controls by using light having high intensity and excellent stability.
An information signal with suppressed noise can be obtained, and tracking and the like can be controlled with high accuracy.

Further, the present invention is characterized in that the monitor light detecting means is provided integrally with the semiconductor laser device.

According to the present invention, since the monitor light detecting means is integrally provided in the semiconductor laser device, the problem of the mounting space of the optical members can be solved, so that the optical pickup device can be miniaturized. It will be possible.

[0029]

1 is a perspective view showing a simplified configuration of a semiconductor laser device 21 according to a first embodiment of the present invention, and FIG. 2 is equipped with the semiconductor laser device 21 shown in FIG. FIG. 3 is a schematic sectional view showing a simplified configuration of the optical pickup device 22, and FIG. 3 is an enlarged view of a main part of FIG. 2.

The semiconductor laser device 21 includes a first semiconductor laser chip 23 that emits light, and a beam splitter 25 that transmits and / or reflects the emitted light from the first semiconductor laser chip 23 and the reflected light from the optical recording medium 24. When,
The wavelength separating optical element 2 including a reflection mirror 26 that further reflects the light reflected by the beam splitter 25.
7, a first optical element 28 disposed between the first semiconductor laser chip 23 and the wavelength separating optical element 27 for diffracting the light emitted from the first semiconductor laser chip 23, and a wavelength separating optical element 27. Is also arranged near the first semiconductor laser chip 23 and the reflection mirror 26 of the wavelength separating optical element 27
A second optical element 29 for diffracting the light reflected by
The light detecting means 30 receives the light diffracted by the second optical element 29.

The first semiconductor laser chip 23 emits red light having a wavelength of 650 nm, which is used when a DVD which is the optical recording medium 24 is used, for example. Light detecting means 30
Is composed of a plurality of light receiving elements, receives the reflected light from the optical recording medium 24, converts it into an electric current corresponding to the amount of the light, and obtains a detection signal of the reflected light. First semiconductor laser chip 23
And the light detecting means 30 is provided on a heat sink (not shown),
The radiator is attached to the first member 31 made of metal such as steel. The first semiconductor laser chip 23 and the light detection means 30 are electrically connected to a lead pin (not shown) by a gold wire, and the lead pin is the lead frame 3.
2 electrically connected. First semiconductor laser chip 23
And the 2nd member 33 which consists of metal, such as steel, is joined with the 1st member 31 so that the light detection means 30 may be covered.

The wavelength separating optical element 27 comprises a beam splitter 25 and a reflecting mirror 26. The polarization beam splitter 25 is used as the beam splitter 25.
Since the laser light emitted from the semiconductor laser chip has the property that the polarization directions are aligned, most of the light is aligned in the main polarization direction in one direction, but some light having a polarization direction different from the main polarization direction is Mixed.

The ratio of the light having a polarization direction different from the main polarization direction to the light having the main polarization direction is about 1 / in a low-power semiconductor laser chip used when reproducing information on an optical recording medium. 50-1 / 100
In a high-power semiconductor laser chip used for recording information, about 1/500 to 1/100
It is 0. This ratio is called the polarization ratio.

The polarization beam splitter 25 transmits the light of the main polarization direction and reflects a part of the light having the polarization direction different from the main polarization direction, so that the light amount of the light condensed on the optical recording medium 24 is changed. The part of the light can be extracted with almost no decrease, and the output of the first semiconductor laser chip 23 can be controlled by using the extracted part of the light as described later. Further, the beam splitter is not limited to the polarization beam splitter, and may be a half mirror capable of selecting a desired transmittance or reflectance. The reflection mirror 26 reflects the light reflected by the polarization beam splitter 25 toward the second optical element 29.

The first and second optical elements 28 and 29 are provided on the first hologram element 34. First optical element 28
Is the diffraction grating 28, and is the first semiconductor laser chip 2
The light emitted from 3 is diffracted into first-order diffracted light, zero-order diffracted light, and −1st-order diffracted light. The diffracted light is used for tracking control and the like. The second optical element 29 is the hologram 2
9, the light reflected by the reflection mirror 26 is diffracted and guided onto the light detecting means 30.

An optical pickup device 22 which is another embodiment of the present invention including the semiconductor laser device 21 is arranged between the semiconductor laser device 21 and the optical recording medium 24, and emits light emitted from the semiconductor laser device 21. Condensing means 35 for condensing on the optical recording medium 24, and monitor light detecting means 36 for receiving the light reflected by the polarization beam splitter 25 provided in the semiconductor laser device 21 and monitoring the output of the first semiconductor laser chip 23. Including and

Optical recording medium 24, for example, the aforementioned DVD
Has a thin disk-like shape with a diameter of 12 cm, and is formed, for example, by vapor-depositing aluminum on the surface of a polycarbonate substrate and coating a resin protective film on the aluminum vapor-deposited layer. The optical recording medium 24 is widely used as a recording medium capable of random access, easy to handle, and capable of recording a large amount of information.

The condenser means 35 is a collimator lens 37.
And an objective lens 38. Collimating lens 37
Converts the light emitted from the first semiconductor laser chip 23 into parallel light. The objective lens 38 transmits the incident light to the optical recording medium 2
4 is focused on the information recording surface to form a light spot on the information recording surface.

The monitor light detecting means 36 is a light receiving element for receiving light and converting it into an electric signal, and the first semiconductor laser chip 2 reflected by the polarization beam splitter 25.
Part of the emitted light of 3 is received and the laser output is monitored.
The detected optical output of the first semiconductor laser chip 23 is AP, which is a system controller including a CPU (not shown).
Input to C. The APC responds to the photodetection output with a first
The output of the first semiconductor laser chip 23 is kept constant by controlling the drive current of the semiconductor laser chip 23.

The light emitted from the first semiconductor laser chip 23 is split by the diffraction grating 28 into first-order diffracted light, zero-order diffracted light and −1st-order diffracted light, and the polarization beam splitter 2
A part of the light is reflected by the monitor light detector 5 onto the monitor light detector 36. The light transmitted through the polarization beam splitter 25 is collimated by the collimator lens 37, and then condensed by the objective lens 38 onto the optical recording medium 24 to form a light spot, thereby recording or recording information on the optical recording medium 24. Playback is performed.

The light reflected from the optical recording medium 24 is reflected by the polarization beam splitter 25 and the reflection mirror 26, enters the hologram 29, and is diffracted. The first-order diffracted light of the diffracted reflected light is received on the light detection means 30,
A detection signal, for example, a tracking servo signal is obtained based on the amount of light received.

According to the present embodiment, since the first semiconductor laser chip 23 is not affected by the reflected light from the optical recording medium 24, a part of the light emitted from the first semiconductor laser chip 23 is obtained. Can be used to control the output of the first semiconductor laser chip 23 with high accuracy so as to be constant. Further, since the light emitted from the first semiconductor laser chip 23 to the optical recording medium 24 is transmitted and diffracted by only one optical element, the light is condensed on the optical recording medium 24 without substantially reducing the light amount of the emitted light. can do.

Further, since the optical pickup device 22 can record or reproduce information on the optical recording medium 24 and perform various controls by using light having high intensity and excellent stability, an information signal in which noise is suppressed is provided. Can be obtained, and tracking and the like can be accurately controlled.

FIG. 4 is a perspective view showing a simplified configuration of a semiconductor laser device 39 according to a second embodiment of the present invention, and FIG. 5 is an optical pickup device 40 including the semiconductor laser device 39 shown in FIG. 6 is a schematic cross-sectional view showing a simplified configuration of FIG. 6, and FIG. 6 is an enlarged view of a main part of FIG.

The semiconductor laser device 39 of this embodiment is
The semiconductor laser device 21 is similar to the semiconductor laser device 21 of the first embodiment, and corresponding parts are designated by the same reference numerals and the description thereof will be omitted. It should be noted that the semiconductor laser device 39 includes a second semiconductor laser chip 41 arranged adjacent to the first semiconductor laser chip 23 and emitting light having a different wavelength from the first semiconductor laser chip 23, and a hologram 29 and wavelength separation. Another hologram 42 which is a third optical element 42 arranged between the optical element 27 for use and diffracting the light reflected by the reflection mirror 26.

The second semiconductor laser chip 41 emits infrared light having a wavelength of 780 nm which is used when a CD is used, for example. In the present embodiment, the semiconductor laser device 3
Since 9 has the first and second semiconductor laser chips 23 and 41, it is possible to record or reproduce information on two different types of optical recording media. First or second
One of the semiconductor laser chips 23 and 41 is automatically selected depending on the type of the optical recording medium 24 used. The two types of optical recording media 24 used for recording or reproducing information, that is, the CD 24a and the DVD 24b, have different thicknesses from the surface to the information recording surface.
Can be switched to an objective lens corresponding to each optical recording medium. A bifocal objective lens may be used as the objective lens so as to be compatible with two different types of optical recording media.

The other hologram 42 diffracts the light reflected by the reflection mirror 26 and guides it to the hologram 29. The other hologram 42 is the second hologram element 4
It is provided in 3. The second hologram element 43 is mounted between the wavelength separating optical element 27 and the first hologram element 34.

The light 44 emitted from the second semiconductor laser chip 41 is diffracted by the diffraction grating 28 into first-order diffracted light, zero-order diffracted light and −1st-order diffracted light. The diffraction grating 28 may have a characteristic of diffracting only one of the lights emitted from the first and second semiconductor laser chips 23 and 41. The diffracted light is polarized by the beam splitter 25.
Part of the light that is incident on and is emitted from the monitor light detection means 36.
And the remaining light is transmitted, is transmitted through the collimator lens 37 and the objective lens 38, and is condensed on the CD 24a.

The light reflected from the CD 24a passes through the objective lens 38 and the collimator lens 37, and enters the polarization beam splitter 25 again. The light reflected by the polarization beam splitter 25 toward the reflection mirror 26 is reflected by the reflection mirror 26 and diffracted by another hologram 42, and the first-order diffracted light passes through the hologram 29 and is received by the light detection means 30. To be done.

The reflected light from the DVD 24b of the light 45 emitted from the first semiconductor laser chip 23 passes through the other hologram 42 and is diffracted by the hologram 29, and the first-order diffracted light is received on the photodetection means 30. . A detection signal, for example, a tracking servo signal is obtained based on the amount of received light.

FIG. 7 is a perspective view showing a simplified structure of a semiconductor laser device 46 according to a third embodiment of the present invention, and FIG. 8 is an optical pickup device including the semiconductor laser device 46 shown in FIG. It is a schematic sectional drawing which simplifies and shows the structure of 47, and FIG. 9 is a principal part enlarged view of FIG.

The semiconductor laser device 46 of this embodiment is
The semiconductor laser device 21 is similar to the semiconductor laser device 21 of the first embodiment, and corresponding parts are designated by the same reference numerals and the description thereof will be omitted. It should be noted that the semiconductor laser device 46 includes the second semiconductor laser chip 41 which is arranged adjacent to the first semiconductor laser chip 23 and emits different wavelengths, and the optical recording medium 24.
Of the reflected light from the above, a wavelength separation optical element 49 including a polarization beam splitter 48 that reflects the reflected light of one wavelength and transmits the reflected light of the other wavelength, a wavelength separation optical element 49, and a diffraction grating 28. And a fourth optical element 50 for diffracting the reflected light transmitted by the polarization beam splitter 48.

The fourth optical element 50 is yet another hologram 50, which includes the diffraction grating 28 and the hologram 2.
9 and the fourth hologram element 51. Still another hologram 50 diffracts the light that has passed through the polarization beam splitter 48 and is incident, and guides it onto the light detection means 30. Further, since the hologram 29 and the further hologram 50 are provided in the one plane 52 of the fourth hologram element 51 which is a plane orthogonal to the axis of the light 45 emitted from the first semiconductor laser chip 23, the hologram 29 and the other hologram 50 are provided. The size reduction of the semiconductor laser device 46 can be realized without causing a problem of the installation space.

The light 44 emitted from the second semiconductor laser chip 41 is diffracted by the diffraction grating 28 into first-order diffracted light, zero-order diffracted light, and −1st-order diffracted light, and further passes through another hologram 50. A part of the emitted light is reflected by the polarization beam splitter 48, and the remaining light transmitted in the direction of the CD 24a passes through the collimator lens 37 and the objective lens 38 and is condensed on the CD 24a. CD24
The light reflected from a passes through the polarization beam splitter 48, is diffracted by another hologram 50, and the −1st order diffracted light is received on the photodetection means 30.

The light 45 emitted from the first semiconductor laser chip 23 passes through the diffraction grating 28 and yet another hologram 50, a part of the light is reflected by the polarization beam splitter 48, and the remaining light is condensed. After being condensed and reflected on the DVD 24b by the means 35, it is incident on the polarization beam splitter 48 and reflected. The light reflected by the polarization beam splitter 48 is reflected by the reflection mirror 26 and enters the hologram 29. Hologram 2
The first-order diffracted light diffracted by 9 is received on the light detection means 30. First and second semiconductor laser chips 23,
The lights 45 and 44 emitted from 41 are received on the same light detecting means 30, and a detection signal is obtained based on the light amount of the detected light.

A polarization prism can be used as the polarization beam splitter 48. When a polarizing prism is used, the light 45, 44 emitted from the first or second semiconductor laser chip 23, 41 is split into polarized light of an electric field component and polarized light of a magnetic field component by the polarizing prism, and the polarized light of one component is polarized. Is transmitted, and the polarized light of the other component is reflected and received on the monitor light detection means 36. For example, the light 45 emitted from the first semiconductor laser chip 23 has a characteristic that the polarized light of the electric field component is reflected, and the light 44 emitted from the second semiconductor laser chip 41 has the characteristic that the polarized light of the magnetic field component is reflected. You can have it. The polarization of the magnetic field component of the light 45 emitted from the first semiconductor laser chip 23 reflected from the optical recording medium 24 is reflected in the direction of the reflection mirror 26 and the electric field of the light 44 emitted from the second semiconductor laser chip 41. The polarized light of the component is transmitted and is incident on another hologram 50.

According to the second and third embodiments, two semiconductor laser chips 23 and 41 which respectively emit lights of different wavelengths are used, and two different types of optical recording media 2 are used.
It becomes possible to record or reproduce information on 4a and 24b.

FIG. 10 is a schematic sectional view showing a simplified structure of an optical pickup device 53 according to a fourth embodiment of the present invention. Optical pickup device 53 of the present embodiment
Is similar to the optical pickup device 22 according to the other embodiment, and corresponding parts are designated by the same reference numerals and the description thereof will be omitted. It should be noted that the monitor light detection means 54 is
That is, it is provided integrally with the semiconductor laser device 21.

In the present embodiment, the monitor light detecting means 54
Are provided integrally with the wavelength separating optical element 27 included in the semiconductor laser device 21. This solves the problem of the mounting space of the optical members, so that the optical pickup device 53 can be downsized. In the present embodiment, the monitor light detection means 54 is
Although provided integrally with the wavelength separating optical element 27, the semiconductor laser device 21 is not limited to this.
The monitor light detection means 54 may be integrally provided with any of the members provided in.

[0060]

As described above, according to the present invention, the output of the semiconductor laser chip can be accurately controlled by utilizing a part of the light emitted from the semiconductor laser chip. Further, since the light emitted from the semiconductor laser chip is transmitted and diffracted by only one optical element, the light can be emitted to the optical recording medium without substantially reducing the light amount of the emitted light.

Further, according to the present invention, by providing two optical elements, the light emitted from each semiconductor laser chip can be diffracted in a desired direction and received by the light detecting means, so that light of different wavelengths can be received. It is possible to record or reproduce information on or from two different types of optical recording media by using two semiconductor laser chips that emit light.

According to the invention, the second optical element and the fourth optical element
Since the optical element and the optical element are provided in the same plane, the semiconductor laser device can be miniaturized without causing a problem of mounting space of the optical member.

Further, according to the present invention, by selecting the polarization beam splitter so as to transmit the light of the main polarization direction of the laser light and reflect the part of the light having the polarization direction different from the main polarization direction. The output of the semiconductor laser chip can be controlled with almost no reduction in the amount of light focused on the optical recording medium.

Further, according to the present invention, since the optical pickup device can record or reproduce information on the optical recording medium and perform various controls by using light having high intensity and excellent stability, accurate information can be obtained. It is possible to perform signal acquisition and various controls.

Further, according to the present invention, by providing the monitor light detecting means integrally with the semiconductor laser device, the problem of the mounting space of the optical members can be solved, so that the optical pickup device can be miniaturized. It becomes possible to do.

[Brief description of drawings]

FIG. 1 is a perspective view showing a simplified configuration of a semiconductor laser device 21 according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a simplified configuration of an optical pickup device 22 including the semiconductor laser device 21 shown in FIG.

FIG. 3 is an enlarged view of a main part of FIG.

FIG. 4 is a perspective view showing a simplified configuration of a semiconductor laser device 39 according to a second embodiment of the present invention.

5 is a schematic cross-sectional view showing a simplified configuration of an optical pickup device 40 including the semiconductor laser device 39 shown in FIG.

FIG. 6 is an enlarged view of a main part of FIG.

FIG. 7 is a perspective view showing a simplified configuration of a semiconductor laser device 46 according to a third embodiment of the present invention.

8 is a schematic sectional view showing a simplified configuration of an optical pickup device 47 including the semiconductor laser device 46 shown in FIG.

9 is an enlarged view of a main part of FIG.

FIG. 10 is a schematic sectional view showing a simplified configuration of an optical pickup device 53 according to a fourth embodiment of the present invention.

FIG. 11 is a system diagram showing a simplified configuration of a conventional optical pickup device 1.

FIG. 12 is a schematic cross-sectional view showing a simplified configuration of another conventional optical pickup device 14.

[Explanation of symbols]

21 Semiconductor laser device 22 Optical pickup device 23 Semiconductor laser chip 24 Optical recording medium 25 beam splitter 26 Reflection mirror 27 Optical element for wavelength separation 28 First optical element 29 Second optical element 30 light detection means 31 First member 32 lead frame 33 Second member 34 First Hologram Element 35 Condensing means 36 Optical detection means for monitor

Claims (7)

[Claims] 1. A semiconductor laser device that emits light toward an optical recording medium in which information is recorded or reproduced by light and receives reflected light from the optical recording medium, and a semiconductor laser chip that emits light. A wavelength splitting optical element including a beam splitter that transmits and / or reflects light emitted from a laser chip and reflected light from an optical recording medium, and a reflection mirror that further reflects light reflected by the beam splitter, and a semiconductor laser A first optical element arranged between the chip and the wavelength separating optical element to diffract light emitted from the semiconductor laser chip; and a wavelength separating optical element arranged closer to the semiconductor laser chip than the wavelength separating optical element. A second optical element that diffracts the light reflected by the reflection mirror, and an optical detector that receives the light diffracted by the second optical element. The semiconductor laser device which comprises a means. 2. A third optical element, which is disposed between the second optical element and the wavelength separating optical element and diffracts light reflected by the reflection mirror, the light detecting means includes the third optical element. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is provided so as to receive light diffracted by an optical element and light diffracted by the second optical element. 3. A fourth optical element disposed between the wavelength separating optical element and the first optical element for diffracting the light transmitted by the beam splitter, wherein the light detecting means includes the fourth optical element. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is provided so as to receive light diffracted by an optical element and light diffracted by the second optical element. 4. The semiconductor laser according to claim 3, wherein the second optical element and the fourth optical element are provided in the same plane orthogonal to the axis of light emitted from the semiconductor laser chip. apparatus. 5. The beam splitter is a polarizing beam splitter.
5. The semiconductor laser device according to any one of 4 to 4. 6. A semiconductor laser device according to claim 1, wherein the semiconductor laser device is disposed between the semiconductor laser device and the optical recording medium, and the light emitted from the semiconductor laser device is directed onto the optical recording medium. An optical pickup device comprising: a condensing means for condensing light and a monitor photodetection means for receiving light reflected by a beam splitter provided in the semiconductor laser device and monitoring the output of the semiconductor laser chip. 7. The optical pickup device according to claim 6, wherein the monitor light detection means is provided integrally with the semiconductor laser device.