JPH07161060A - Optical pickup device - Google Patents

Abstract

PURPOSE:To miniaturize a device, to reduce the weight of the device and to reduce the cost of the device by integrating the optical system of an optical pickup device for a magneto-optical disk. CONSTITUTION:A light from a semiconductor laser 1 is converged on a magneto- optical disk 9. A magneto-optical signal is detected by guiding one part of a reflected light from the magneto-optical disk 9 to an optical wave guide element 11 with a diffraction element 6. A releaf type hologram in which a periodic construction having a period shorter than the wave-length of the light is superposed is used as the diffraction element 6. A control signal is detected by guiding a remaining reflected light transmitting through the diffraction element 6 to a pentapartite photodetector 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information reproducing apparatus, and more particularly to an optical pickup apparatus which can be miniaturized and integrated in an optical system and can be suitably used in a magneto-optical disk apparatus or the like.

[0002]

2. Description of the Related Art Optical discs capable of recording a large amount of information with high density have been used in many fields in recent years. In an optical information reproducing apparatus using such an optical disc as an information recording medium, downsizing and weight saving of an optical pickup device (hereinafter referred to as an optical pickup) is a particularly important issue. In order to solve this problem, it is very effective to use a diffraction element in the optical system of the optical pickup, and some proposals have been made so far.

FIG. 6 shows a first conventional example of an optical pickup using a diffraction element in an optical system. The optical pickup shown here is Y. Yoshida et al .: '' Three Beam CD Optica.
l Pickup using a Holographic Optical Element, `` Pr
oc. Optical Data Strage Technologies, SPIE 1401, (1
990), p.58.

In this optical pickup, the divergent light emitted from the semiconductor laser 101 is the first diffraction element 1.
The 0th-order diffracted light (main beam) and the ± 1st-order diffracted light (sub-beam) for detecting tracking deviation by 02.
Is divided into and The divided divergent light passes through the second diffraction element 103 and is condensed on the information recording surface of the optical disc 106 by the collimator lens 104 and the objective lens 105. Then, the main beam in the divergent light forms a focused spot 108a on the optical disc 106, and the sub beam forms two focused spots 108b and 108c.

On the other hand, the reflected light from the optical disc 106 is
After being taken into the optical system again by the objective lens 105 and passing through the collimator lens 104, the second diffraction element 1
03, and the diffracted light is condensed on the photodetector 107.

Here, as shown in FIG. 6, the pattern of the first diffraction element 102 is such that straight lines are arranged in parallel at regular intervals. The pattern of the second diffraction element 103 is formed by arranging curves suitable for condensing the reflected light on the photodetector 107.

In the current optical information reproducing apparatus, it is necessary to focus the light beam on the disc-shaped optical disk 106 into a spot light having a diameter of about 1 μm by the objective lens 105 and to follow the information track 112. Therefore, a focus detection mechanism that detects a focus control signal and a tracking detection mechanism that detects a tracking control signal are indispensable. The details of these detection mechanisms will be described below.

(Focus Detection Mechanism) First, the focus detection mechanism will be described. The second diffractive element 1 described above
Reference numeral 03 is substantially circular and has two semi-circular regions 103a and 103b divided into two by the dividing line DL. On the other hand, the photodetector 107 has five photodetector sections 107a, 107b, 107 divided by four dividing lines A, B, C, D.
c, 107d and 107e.

Diffracted by the first diffractive element 102,
Of the reflected light of the main beam that is reflected after being condensed on the optical disc 106, the light diffracted by the one semicircular region 103a of the second diffraction element 103 is the photodetector 1
The light is condensed at 07 to form a condensed spot 111a on the dividing line A. On the other hand, the light diffracted by the other semi-circular region 103b forms a focused spot 111a 'on the photodetector 107c.

Further, the reflected light of the sub-beam which is condensed on the optical disc 106 and forms the converging point 108b, is reflected by the two converging spots 111 on the photodetector 107d.
b ', 111b' are formed. After the light is condensed on the optical disc 106 to form the light condensing point 108c, the reflected light of the sub-beam that is reflected forms two light condensing spots 111c and 111c 'on the photodetector 107e.

In such a structure, when the divergent light from the semiconductor laser 101 is accurately focused on the optical disc 106 by the objective lens 105, that is, in the focused state, the half of the second diffractive element 103 is inspected. The focused spot 111a of the diffracted light from the circular area 103a is shown in FIG.
As shown in (b), 1 on the dividing line A of the photodetector 107
Formed in points. Therefore, the photodetectors 107a and 10a
The outputs of 7b become equal.

On the other hand, when the optical disk 106 approaches the objective lens 105 for some reason, the focal point of the diffracted light is formed behind the photodetector 107. Therefore, at this time, as shown in FIG.
1a spreads in a semicircular shape in the photodetector 107a. On the contrary, when the optical disc 106 moves away from the objective lens 105, the focal point of the diffracted light is formed in front of the photodetector 107. Therefore, at this time, as shown in FIG. 7C, the focused spot 111a spreads in a semicircular shape in the photodetector 107b.

Therefore, assuming that the output signals of the photodetectors 107a and 107b are S1 and S2, respectively, the focus error signal FES can be obtained by the calculation of the following equation. Specifically, this calculation is performed by a subtractor.

FES = S1-S2 ... When the focus error signal FES is obtained in this way, an actuator (not shown) drives the objective lens 105 based on this servo signal, whereby the focused spot 108a on the information track 112. Controlled to be tied together.

(Tracking Detection Mechanism) Next, the tracking detection mechanism in the optical pickup will be described. FIG. 8 shows the positional relationship between the focused spot on the optical disc 106 and the information track 112. As shown in FIG. 8B, the focused spots 108 b, 10 of the two sub-beams are formed.
8c has a symmetrical positional relationship in the direction of the information track 112 with the focused spot 108a of the main beam at the center, and is slightly offset in the opposite direction with respect to the information track 112.

As shown in FIG. 8A, if the information track 112 is displaced to the left side in the figure with respect to the focused spot 108a for some reason, the focused spot 108b is obtained.
Is located almost above the information track 112, the intensity of the reflected light is reduced. On the other hand, the focused spot 1
Since 08c moves away from the information track 112, the intensity of its reflected light increases.

On the other hand, as shown in FIG. 8C, when the information track 112 shifts to the right side of the drawing with respect to the focused spot 108a, the opposite phenomenon occurs. That is, since the focused spot 108b is separated from the information track 112, the intensity of the reflected light increases, and the focused spot 108c
Is located almost above the information track 112, the intensity of the reflected light is reduced.

Then, the focused spots 108b, 108c
Since the reflected lights of are collected on the photodetectors 107d and 107e, respectively, assuming that the output signals of the photodetectors 107d and 107e are S4 and S5, the tracking error signal TES is obtained.
Can be obtained by calculating the following equation. This calculation is also performed by the subtractor.

FES = S4-S5 ... When the tracking error signal TES is obtained in this way, an actuator (not shown) drives the objective lens 105 based on this servo signal, whereby the focused spot 108a on the information track 112. Controlled to be tied together.

FIG. 9 shows an optical pickup which further embodies the first conventional example shown in FIG. In this optical pickup, the first diffraction element 102 and the second diffraction element 103 are formed on the lower surface and the upper surface of the glass substrate 109 by etching. Semiconductor laser 1
01 and the photodetector 107 are arranged in a hermetically sealed box-shaped can package 110.

FIG. 10 shows a second conventional example of an optical pickup using a diffraction element in the optical system. This optical pickup is a so-called one-beam type optical pickup. For simplification, the same elements as those in FIG. 9 have the same numbers. The difference between the second conventional example and the first conventional example is that the glass substrate 1
14 is that the diffraction element 113 is formed only on the lower surface of 14 and that the photodetector 115 is divided into four. The semiconductor laser 101 and the photodetector 107 are hermetically sealed as in the first conventional example. Box-shaped can package 1
It is located within 10.

Since the focus detecting mechanism and the tracking detecting mechanism in the second conventional example have many parts which are the same as those in the first conventional example, they are omitted here. Details are Y.
Kurata et al .: '' CD Optical Pickup using a Compute
r Generated Holographic Optical Element, '' Proc. O
ptical Data Strage and Scanning Technologies, SPIE
1139, (1989), p161.

In the optical pickup in which the optical system is miniaturized and integrated by using the diffraction element as described above, since the light source and the photodetector are arranged in the same package, the environment resistance is excellent and the size and weight are small. It has the feature of being low-priced.

By the way, recently, with the spread of optical discs, a magneto-optical disc has attracted attention as a rewritable optical disc. A diffractive element is also used in the optical system of the pickup.

FIG. 11 shows a conventional example of a magneto-optical disk pickup using a diffraction element in the optical system. In this magneto-optical disc pickup, the semiconductor laser 201 is used.
The divergent light emitted from is transmitted through the diffractive element 202 as the 0th-order light, converted into parallel light by the collimator lens 203, and then transmitted through the compound prism 204.
The light is focused on the magneto-optical disk 207 via the mirror 205 and the objective lens 206.

The reflected light from the magneto-optical disk 207 is again taken into the optical system by the objective lens 206, and a part of the light is reflected by the compound prism 204 and the collimator lens 203.
After being transmitted, the light is diffracted by the diffraction element 202 and focused on the photodetector 209, and is used for detecting a focus shift (focusing error) and a tracking shift (tracking error). Although not shown here, the pattern of the diffractive element 202 is such that curved lines suitable for focusing the diffracted light on the photodetector 209 are arranged in parallel.

Since the focus detection mechanism and the tracking detection mechanism have many parts that overlap with those of the conventional example of the optical pickup described above, they are omitted here. Details are described in "Sato, et al .: Pickup for 3.5-inch magneto-optical disk," Sharp Technical Report, No. 50, pp20-24 (1991).

On the other hand, the remaining reflected light that is reflected twice in the compound prism 204 and reaches the Wollaston prism 210 is separated into two different polarized lights by the Wollaston prism 210, and then divided into two by a condenser lens 211. The light is focused on the photodiode 212. Therefore, the information signal is reproduced by taking the difference between the outputs of the two-divided photodiode 212.

FIG. 12 shows the principle of detecting a magneto-optical signal. As is well known, when a medium such as a magneto-optical disk is irradiated with P-polarized light, the polarization direction is rotated by θk or −θk depending on the direction of the magnetism at the irradiation position and is reflected. The rotation direction of this plane of polarization becomes an information signal, but in order to detect this, the reflected light is generally ±± as shown in FIG.
The polarization components of 45 ° azimuth are separated and the intensity difference between the two polarization components is calculated. Therefore, the crystal orientation of the Wollaston prism 210 is determined to be suitable for this.

Further, the rotation angle θk or −θk of the plane of polarization is
Is a minute angle of about 1 °. Therefore, the compound prism 2
In order to improve the S / N ratio of the signal by apparently increasing the rotation amount of the polarization plane, the reflecting surface 213 of 04 has polarization characteristics such that 100% of S-polarized light and 20% of P-polarized light are reflected. Has been done.

[0031]

In the first conventional example and the second conventional example of the optical pickup described above, the optical system is miniaturized and integrated using the diffraction element, and the light source and the photodetector are arranged in the same package. Therefore, it is small and lightweight, and is suitable for read-only and write-once disc devices. Also, it has excellent environmental resistance. However, it cannot be applied to a rewritable magneto-optical disk device because it has no function of detecting a magneto-optical signal.

On the other hand, in the conventional example of the magneto-optical disk pickup, the use of the diffractive element is intended to reduce the size and weight of the optical system. However, the prism is still used in the optical system for detecting the magneto-optical signal, which hinders the fundamental reduction in size and weight. Further, since the Wollaston prism used for polarization separation is made of expensive crystal, it is an obstacle in reducing the cost of the optical pickup.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an optical pickup device which can be applied to a rewritable magneto-optical disk device and which is small in size and light in weight and low in cost. .

[0034]

An optical pickup device of the present invention comprises a light source, an optical system for condensing light from the light source on a record carrier and condensing reflected light from the record carrier,
An optical branching unit that is provided in the optical path of the reflected light and branches a part of the reflected light; an information signal detection unit that collects the reflected light branched by the optical branching unit and detects an information signal; An optical pickup device comprising: a control signal detection unit that collects the remaining reflected light that has passed through the light branching unit and detects a control signal, wherein the light branching unit has a wavelength of light from the light source. It is a relief type hologram in which a periodic structure having a shorter period is superposed, and the information signal detecting section is an optical waveguide element for detecting the polarization state of reflected light, whereby the above object is achieved.

Preferably, the light source, the information signal detector and the control signal detector are arranged in the same package.

[0036]

In a relief hologram in which a periodic structure having a period shorter than the wavelength of light is superimposed, due to structural birefringence, the diffraction efficiency differs between a polarized component parallel to the periodic structure and a polarized component orthogonal to the periodic structure. . By utilizing this property, a part of the reflected light is guided to the information signal detecting section without using the prism. Here, when an optical waveguide element is used as the information signal detecting section, the polarization state of the reflected light is detected without using the prism even in the information signal detecting section. Therefore, according to such a configuration, a high-quality information signal can be detected without using a prism.

[0037]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an optical pickup device of the present invention. This optical pickup is an optical pickup for a magneto-optical disk. The configuration will be described below together with the operation.

The divergent light emitted upward from the semiconductor laser 1 is a 0th-order diffracted light (main beam) by the first diffractive element 3 provided on the lower surface of the first glass substrate 2.
And the ± first-order diffracted light (sub-beam) for detecting the tracking deviation. Subsequently, the divided divergent light is divided into the second diffraction element 4 provided on the upper surface of the first glass substrate 2 and the upper surface of the second glass substrate 5 superposed on the first glass substrate 2. The light is sequentially transmitted through the third diffractive element 6 provided in the and, and is guided to the collimator lens 7. Subsequently, the light beam made into parallel light by the collimator lens 7 is condensed on the magneto-optical disk 9 by the objective lens 8.

On the other hand, the reflected light from the magneto-optical disk 9 is
It is taken into the optical system again by the objective lens 8 and transmitted through the collimator lens 7, and a part thereof is diffracted by the third diffractive element 6 and condensed on the optical waveguide element 11.

The third diffractive element 6 and the optical waveguide element 11 are the optical branching means and the information signal detecting section in the optical pickup device of the present invention, respectively. As shown in FIG. 2, the optical waveguide device 11 has a silicon substrate 16 on which a photodetector 15 is formed. On the surface of the silicon substrate 16, an optical waveguide 13, an optical coupler 12 that guides diffracted light into the optical waveguide 13, and two polarized lights that propagate through the optical waveguide 13,
That is, the polarization separation element 14 for separating the TE polarized light and the TM polarized light
And are formed. The diffracted light focused on the optical waveguide element 11 is guided into the optical waveguide 13 by the optical coupler 12, is separated into TE polarized light and TM polarized light by the polarization separation element 14, and is incident on the photodetector 15. . The photodetector 15 is
The magneto-optical signal, that is, the information signal is reproduced by calculating the difference between the outputs of the TE polarized light and the TM polarized light.

The remaining reflected light that has passed through the third diffractive element 6 is diffracted by the second diffractive element 4 and enters the five-division photodetector 10. The five-division photodetector 10 is a control signal detection unit in the optical pickup device of the present invention, and by processing the electric signal from the five-division photodetector 10, the control signals for focus control and tracking control are generated. can get.

The semiconductor laser 1 serving as a light source, the optical waveguide device 11 and the five-division photodetector 10 are arranged in a can package 20 which is hermetically sealed. Further, the first glass substrate 2 and the second glass substrate 5 are
The can package 20 is arranged so as to overlap. The can package 20 has a cylindrical shape.

The principle of detecting a magneto-optical signal (information signal) and the principle of detecting a control signal in the optical pickup device of the present invention will be described below.

(Principle of Detecting Magneto-Optical Signal) FIG. 3 shows the third diffractive element 6, the 5-split photodetector 10 and the optical waveguide element 11.
FIG. 4 is a plan view showing the positional relationship between the collimator lens 7 and the collimator lens 7. The intersection of the X-axis and the Y-axis is the optical axis, the five-division photodetector 10 is deviated by an appropriate distance from the optical axis in the -X direction, and the optical waveguide element 11 is deviated by -45 ° from the X-axis. Each is arranged.

FIG. 4 is a perspective view showing the surface structure of the third diffraction element 6. The third diffraction element 6 is a relief type hologram having a grating pitch A, and the surface of each grating has
A periodic structure having a period B shorter than the wavelength of light from the light source is formed parallel to the X axis.

Here, in a periodic structure shorter than the wavelength of light, a phenomenon called structural birefringence in which the refractive index differs depending on the polarization direction occurs. Therefore, in the third diffractive element 6 as shown in FIGS. 3 and 4, a polarization component parallel to the periodic structure (X direction component) and a polarization component orthogonal to the periodic structure (Y
Direction component), the diffraction efficiency is different, and the polarization component parallel to the periodic structure is almost diffracted and the polarization component orthogonal to the periodic structure is hardly diffracted by adjusting the depth of the grating groove. it can.

Then, for example, a semiconductor laser 1 which is a light source
If the polarization direction of the laser light emitted from the semiconductor laser 1 is set to the Y-axis direction, the light emitted from the semiconductor laser 1 is diffracted by the third diffraction element 6 when traveling toward the magneto-optical disk 9. Since less light is emitted, more light reaches the magneto-optical disk 9 and the light can be effectively used. On the other hand, when reflected by the magneto-optical disk 9, Y
The reflected light whose polarization plane is rotated by θk or −θk from the axis is almost diffracted by the third diffractive element 6 in the X-direction component, but is hardly diffracted by the Y-axis component, so that the polarization plane of the diffracted light is rotated. Apparently becomes large, and as a result, a magneto-optical signal having a good S / N ratio is detected.

FIG. 5 shows polarized light in the optical waveguide 13. Third
Since the diffracted light from the diffractive element 6 is diffracted in the −45 ° direction with respect to the X axis, the polarized component in the −45 ° azimuth of the reflected light is excited in the optical waveguide element 11 as the TM mode,
The polarization component in the + 45 ° azimuth is TE in the optical waveguide device 11.
It is excited as a mode (see FIG. 12). The respective polarization components are spatially separated by the polarization separation element 14 and enter the photodetector 15 to be converted into an electric signal. As a result, a magneto-optical signal, that is, an information signal is detected. And
Information is reproduced by taking the difference between the electric signals of the photodetector 15. This difference is calculated by the subtractor 21 shown in FIG.

(Principle of Control Signal Detection) Next, the principle of control signal detection will be described. The remaining reflected light transmitted through the third diffractive element 6 is, as described above, the second diffractive element 4
Is diffracted by and is incident on the five-division photodetector 10.

The second diffractive element 4 is the second diffractive element 103 used in the first conventional example of the optical pickup described above.
As shown in FIG. 1, it is substantially circular and is divided into two semicircular regions 4a and 4b. The pattern is a curved pattern suitable for converging the reflected light from the magneto-optical disk 9 on the five-division photodetector 10.

The five-division photodetector 10 corresponds to the photodetector 107 of the first conventional example, and its photodetection sections 107a, 107b, 107c, 107d and 1 are provided.
07e corresponding to five photodetectors 10a, 10
b, 10c, 10d and 10e.

Of the main beam reflected after being diffracted by the first diffractive element 3 and condensed on the magneto-optical disk 9, the light diffracted by one region 4a of the second diffractive element 4 is Photodetection units 10a, 10 of the 5-split photodetector 10
On the dividing line L (see FIG. 3) dividing b, the other region 4
The light diffracted by b is detected by the photodetector 10
Condensing spots are formed on c respectively.

After forming two focused spots on the magneto-optical disk 9, one of the reflected lights of the two sub-beams is reflected by one of the sub-beams. A focused spot is formed on 10d.
The reflected light of the other sub-beam forms a focused spot on the photodetection section 10e of the 5-split photodetector 10.

Then, the photodetection section 1 of the five-division photodetector 10
If the output difference between 0a and 10b is detected and the above equation is calculated, the focus error signal FE is obtained as in the first conventional example.
S can be obtained. Similarly, the photodetectors 10d and 10
If the output difference of e is detected and the above equation is calculated, the tracking error signal TES can be obtained as in the first conventional example.

As described above, the optical pickup device of the present invention uses the magneto-optical disk via the third diffractive element 6 which is a relief hologram in which a periodic structure having a period shorter than the wavelength of light is superposed. Since a part of the reflected light from 9 is guided to the optical waveguide element 11 to detect a magneto-optical signal, a high-quality magneto-optical signal can be detected without using a prism. For this reason, an optical system for detecting a magneto-optical signal and an optical system for detecting a control signal are integrated, and a signal detection unit (optical waveguide element 11 and five-division photodetector 10) in each optical system is integrated. Are properly arranged in the can package 20 together with the semiconductor laser 1 as the light source.

The control signal detecting section, that is, the focus detecting mechanism and the tracking detecting mechanism are not limited to those in the above-described embodiment. For example, the method of division by the second diffractive element 4 and the grating in each region are used. The direction of the line and the shape of the photodetector (5-division photodetector 10) for detecting the control signal can be freely selected. Therefore, it is possible to detect the tracking deviation by the one-beam method as in the second conventional example of the optical pickup described above.

Further, together with the photodetectors (the five-division photodetector 10 and the photodetector 15 in the optical waveguide device 11), the current-
If an electronic circuit for voltage conversion and signal amplification is formed on a silicon substrate, it is possible to obtain effects such as being less susceptible to external noise.

Further, when the first glass substrate 2 and the second glass substrate 5 are bonded together with an adhesive, as shown in FIG. 2, the upper glass substrate 5 facing the second diffractive element 4 is joined.
A recess 17 may be provided on the lower surface of the. If you do that,
This is because the adhesive does not reach the second diffractive element 4 and the characteristic deterioration of the diffractive element 4 is prevented.

[0060]

As described above, the optical pickup device of the present invention guides the reflected light from the recording medium to the optical waveguide element via the relief type hologram on which the periodic structure having a period shorter than the wavelength of light is superposed. Therefore, the prism can be excluded from the optical system for detecting the information signal. Therefore, the optical system for detecting the information signal and the optical system for detecting the control signal can be integrally formed, and further, the signal detecting section of each optical system and the light source should be arranged in the same package. You can also Therefore, it can be applied to, for example, a magneto-optical disk pickup, and its size and weight can be greatly reduced and the number of optical components can be reduced. In addition, the packaging improves the environmental resistance performance. Further, since the Wollaston prism that uses expensive crystal is not required, the cost can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an optical pickup device of the present invention.

FIG. 2 is an enlarged sectional view showing a part of the optical pickup of the present invention.

FIG. 3 is a plan view showing a positional relationship among an optical waveguide device, a control signal detection unit, and an optical branching unit in the optical pickup device of the present invention.

FIG. 4 is a perspective view showing a detailed structure of a light branching unit.

FIG. 5 is a plan view showing polarized light in an optical waveguide.

FIG. 6 is a schematic perspective view showing a first conventional example of an optical pickup.

FIG. 7 is a schematic diagram showing a principle of detecting a focus control signal.

FIG. 8 is a schematic diagram showing a detection principle of a tracking control signal.

FIG. 9 is a perspective view of an optical pickup that embodies a first conventional example.

FIG. 10 is a perspective view showing a second conventional example of an optical pickup.

FIG. 11 is a perspective view showing a schematic configuration of a conventional example of a magneto-optical disk pickup.

FIG. 12 is a schematic diagram showing the principle of detecting a magneto-optical signal.

[Explanation of symbols]

 1 Semiconductor Laser 2 1st Glass Substrate 5 2nd Glass Substrate 3 1st Diffraction Element 4 2nd Diffraction Element 6 3rd Diffraction Element 7 Collimating Lens 8 Objective Lens 9 Magneto-Optical Disk 10 5 Split Photodetector 11 Optical waveguide element 12 Optical coupler 13 Optical waveguide 14 Polarization separation element 15 Photodetector 16 Silicon substrate 20 Can package

(72) Inventor Hiroyuki Yamamoto 22-22 Nagaike-cho, Naganocho, Abeno-ku, Osaka-shi, Osaka Prefecture Sharp Co., Ltd.

Claims (2)

[Claims] 1. A light source, an optical system that collects light from the light source on a record carrier and collects reflected light from the record carrier, and the reflected light is provided in an optical path of the reflected light. Light branching means for branching a part of the light, the reflected light branched by the light branching means, and the information signal detecting section for detecting an information signal, and the remaining reflected light transmitted through the light branching means. And a control signal detecting section for detecting a control signal, wherein the optical branching means is a relief type in which a periodic structure having a cycle shorter than the wavelength of light from the light source is superposed. An optical pickup device, which is a hologram, wherein the information signal detection unit is an optical waveguide element that detects the polarization state of reflected light. 2. The optical pickup device according to claim 1, wherein the light source, the information signal detector, and the control signal detector are arranged in the same package.