JPH05250751A - Optical integrated circuit, optical pickup, and optical information processor - Google Patents

Abstract

PURPOSE:To provide a downsized optical pickup by constituting an optical integrated circuit having polarized face detecting function. CONSTITUTION:In the inventive optical integrated circuit 10, optical elements for splitting a light beam on the return path into two types of linearly polarized light are arranged on the path of light beam emitted from a laser element 13 toward the inside of a transparent body 20 and propagates on various optical elements mounted on the surface thereof and a photoelectric integrated circuit board 11. The inventive optical pickup is equipped with an optical integrated circuit 10 comprising a hologram polarized beam splitter 15 for diffracting P-polarized component of light beam on the return path as a zero-order light and S-polarized component as a + or - primary light, and multi-split light detectors 16, 17 for detecting P-polarized component and S-polarized component and subjecting thus detected components to photoelectric conversion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an optical integrated circuit, an optical pickup, and an optical information processing device, and more specifically, it irradiates a disc with a laser beam focused on a fine spot and detects its reflected light. The present invention relates to an optical integrated circuit for reading information, an optical pickup using the optical integrated circuit, and an optical information processing device.

[0002]

2. Description of the Related Art In recent years, the practical application of semiconductor laser devices, which have the advantages of small size, high output, and low cost, has led to the application of lasers to general industrial machines and consumer machines where it has been difficult to use conventional laser light sources. There is. Above all, the progress in the fields of optical disk devices and optical communication is remarkable. It is considered that the semiconductor laser device will be applied to more fields in the future. Using this semiconductor laser element, an integrated optical integrated circuit, a compact and lightweight optical pickup, and an optical information processing apparatus are configured.

FIG. 5 shows a conventional CD (compact disc).
1 shows the configuration of an optical system of an optical pickup for a computer. The optical pickup 110 includes a semiconductor laser 1 arranged in a straight line.
01, the collimator lens 102, the polarization beam splitter 103, the quarter-wave plate 104, and the objective lens 10
5 and an optical disc 106. In addition, the condenser lens 10 is provided in the direction perpendicular to the side of the polarization beam splitter 103.
7, a cylindrical lens 108, and a photodetector 109 are provided.

In this optical pickup 110, the laser light emitted from the semiconductor laser 101 is collimated by the collimator lens 102.
Is collimated by. The collimated laser light passes through the polarization beam splitter 103 and the quarter-wave plate 104, and then is focused on the optical disc 106 by the objective lens 105. The reflected light reflected after being condensed on the optical disc 106 passes through the quarter-wave plate 104 again and is reflected by the polarization beam splitter 103 in the orthogonal direction. The reflected light reflected in the perpendicular direction is collected by the condenser lens 107,
The light is focused on the photodetector 109 through the cylindrical lens 108, and the information on the optical disc 106 is read.

6 (a) and 6 (b) show the structure of an optical integrated circuit for an optical pickup (Our patent application: Acceptance No.
91-5970). This optical integrated circuit 120 has a photodetector 132, a laser element 131, and a multi-segment photodetector 13 on the surface.
3, a hologram beam splitter 134, and an optoelectronic integrated circuit board 130 in which a hologram collimator lens 135 is integrated. A photodetector 132 for laser light output monitoring is formed at an end of the optoelectronic integrated circuit board 130, and a laser element 131 is mounted on the submount 131a in the immediate vicinity.

The optoelectronic integrated circuit board 130 is attached to a die pad 137, and the optoelectronic integrated circuit board 130 and the die pad 137 are molded in a transparent body 138 to form an optical integrated circuit 120. At this time, the optical element 121 is mounted on the surface 138a of the transparent body 138 by molding including a marking technique.

The optical integrated circuit 120 operates as follows. The laser beam emitted from the laser element 131 is a three-beam generation diffraction grating 121 for generating 0th and ± 1st order diffracted light, two types of hologram beam splitters 134 having different pitches, and the hologram collimator lens 1.
After passing through the aspherical objective lens 35, the light is focused on an optical disc (not shown).

The light beam reflected by the optical disk follows the above-mentioned path in reverse, and the hologram beam splitter 13
4, the optical path is deflected, is reflected by the surface 138a of the transparent body 138, is incident on the multi-division photodetector 133 formed on the optoelectronic integrated circuit substrate 130, and is photoelectrically converted. The photoelectrically converted electric signal passes through a signal processing circuit (not shown) formed on the optoelectronic integrated circuit 130, and then passes through the optical integrated circuit 12
It is taken out of 0.

FIG. 7 shows the structure of an optical system conventionally used for an optical pickup of a magneto-optical disk. This optical pickup 140 has a semiconductor laser 141 arranged in a straight line.
, Collimator lens 142, and beam splitter 14
3, an objective lens 144, and an optical disc 145. 1 in the direction perpendicular to the beam splitter 143
A / 2 wavelength plate 146, a condenser lens 147, a polarization beam splitter 149, and a multi-split photodetector 150 are provided. Further, a condenser lens 152 and a multi-split photodetector 151 are arranged in a direction perpendicular to the polarization beam splitter 149.

In this optical pickup 140, the laser light emitted from the semiconductor laser 141 is collimated by the collimator lens 142, and the beam splitter 143.
After passing through, the light is focused on the magneto-optical disk 145 by the objective lens 144. Of the reflected light that is condensed and reflected on the magneto-optical disk 145, the reflected light that is reflected by the beam splitter 143 is the half-wave plate 146 and the condenser lens 1.
After passing through 47, etc., it is split into two by a polarization beam splitter 149 into two directions at right angles. The two split lights are detected by two multi-split photodetectors 150 and 151, respectively.
The focus error signal, the tracking error signal, and the information signal are respectively detected by the operation of the two signals detected by these two multi-segment photodetectors 150 and 151.

[0011]

The optical pickup 110 shown in FIG. 5 and the optical pickup 120 shown in FIG.
Since it is for D, it does not have the function of reading the polarization direction of the laser light reflected from the magneto-optical disk, which is necessary for reading. Therefore, it cannot be used as it is as an optical pickup for a magneto-optical disk.

In the case of a discrete optical system such as the optical pickup 140 shown in FIG. 7, the magneto-optical disc 1 is used.
There is a limit in reducing the size and weight of the 45 optical pickup 140. Further, since a large number of optical elements are used, there is a problem that there are many adjustment points such as alignment during assembly.

The present invention solves the above problems, and an object thereof is to realize an integrated optical integrated circuit capable of reading a magneto-optical disk and having a polarization plane detecting function.
(EN) Provided is a compact and lightweight optical pickup for a magneto-optical disk by reducing the number of extra alignment steps and reducing the cost. Another object of the present invention is to provide an optical information processing device capable of reading an information signal from the difference in light intensity detected by two multi-segment photodetectors.

[0014]

The optical integrated circuit of the present invention comprises:
A laser element, a light receiving element, a control circuit for controlling each of the laser element and the light receiving element, a signal processing circuit, and an optoelectronic integrated circuit board on which various optical elements are integrated, and a transparent body on which various optical elements are integrated. , Which are integrally molded or bonded together, are emitted from the laser element toward the inside of the transparent body, the various optical elements on the surface of the transparent body, and the various types on the optoelectronic integrated circuit substrate. An optical element for separating the polarization plane is provided on the path of the light beam propagating while reflecting between the optical element and the return light beam into two kinds of linearly polarized light. The above object is achieved.

The optical pickup of the present invention comprises a hologram beam splitter for diffracting the light of the P-polarized component of the return light beam as the 0th-order light and the light of the S-polarized component as the 1st-order light, and the P-polarized beam splitter.
A multi-segment photodetector that detects and photoelectrically converts the polarized component light and the S-polarized component light, and an optical integrated circuit having an optical element are provided, thereby achieving the above object.

In the optical information processing apparatus of the present invention, the optical element has a beam splitter and a hologram whose diffraction angles and thicknesses are optimally designed so that the detected light intensities of two types of linearly polarized light are equal, and the polarization direction of the return light beam. 2 when is rotated
Multi-split photodetectors for P-polarization detection and S-polarization detection that determine the rotation of the polarization direction by differentially detecting the light intensity of the linearly polarized light of the species, and both polarizations detected by the multi-split photodetector An optical integrated circuit having an optical element of an information reproducing device for reproducing the information signal of the magneto-optical disk by differentially detecting the light intensity of the component is provided, thereby achieving the above object.

[0017]

The laser light emitted from the semiconductor laser travels inside the transparent body and is incident on the three-beam generating diffraction grating formed on the upper surface of the transparent body. The three 0th-order and ± 1st-order light beams generated by the three-beam generation diffraction grating are condensed on the magneto-optical disk through the hologram beam splitter, the hologram collimator lens, and the aspherical objective lens, and three light beams are collected. Form spots.

The light reflected by the magneto-optical disk travels in the opposite direction, is deflected by the holographic beam splitter, is reflected by the surface of the transparent body, and is multi-segmented photodetector formed on the optoelectronic integrated circuit substrate. The light enters the container and is photoelectrically converted. The photoelectrically converted electrical signal goes through a signal processing circuit,
It is taken out of the optical integrated circuit.

The hologram polarization beam splitter diffracts the light of the polarization component of P polarization as 0th order light and the light of the polarization component of S polarization as 1st order light. Therefore, the P-polarized and S-polarized light components of the incident laser light are detected by different multi-division photodetectors.

With the above structure, an integrated optical integrated circuit having a polarization plane detecting function can be realized. Compared with a conventional optical system that uses a combination of a number of discrete optical components, the number of extra alignment steps is reduced and the cost is reduced. Further, by using this optical integrated circuit, the optical pickup device can be reduced in size and weight.

[0021]

EXAMPLES Examples of the present invention will be described below.

(Embodiment 1) FIG. 1 shows a first embodiment of the optical integrated circuit of the present invention. This optical integrated circuit 10 has an optoelectronic integrated circuit board 11 in which various optical elements such as a semiconductor laser element 13 and a hologram optical element are integrated, and a flat transparent body 20 obtained by molding the optoelectronic integrated circuit board 11 with resin.

The optoelectronic integrated circuit substrate 11 is formed of Si or the like, and the semiconductor laser 13 is mounted on the submount 12 attached thereto. Further, on the left side of the submount 12, a photodetector (PD) 14 for monitoring laser output light, a hologram polarization beam splitter 15,
A multi-segment photodetector 16 for S-polarization detection and a multi-segment photodetector 17 for P-polarization detection are provided. Submount 12
A hologram beam splitter 18 and a hologram collimator lens 19 are respectively provided on the right side of.

The S-polarization detecting multi-segment photodetector 16 and the P-polarization detecting multi-segment photodetector 17 are monolithically formed on the optoelectronic integrated circuit substrate 11 such as Si. The hologram optical element such as the hologram beam splitter 18 is formed by engraving a groove shape on the optoelectronic integrated circuit substrate 11 such as Si by the conventional IC technique. On the surface 20a of the transparent body 20, the three-beam generating diffraction grating 2 is provided.
1. An aspherical objective lens 22 is formed. 3
The beam generating diffraction grating 21 is preferably provided with a metal thin film on its surface in order to increase the reflectance, or is totally reflected by making the incident angle of the light beam larger than the critical angle.

The operating principle of the optical integrated circuit 10 will be described below. The laser light emitted from the semiconductor laser 13 travels inside the transparent body 20 and enters the three-beam generation diffraction grating 21 formed on the upper surface 20 a of the transparent body 20. Three
The 0th order and ± generated by the beam generation diffraction grating 21.
The three primary light beams are focused on a magneto-optical disk (not shown) via the hologram beam splitter 18, the hologram collimating lens 19, and the aspherical objective lens 22 to form three spots.

The light reflected by the magneto-optical disk travels in the opposite direction, is deflected by the hologram beam splitter 18, and enters the hologram polarization beam splitter 15. The hologram polarization beam splitter 15 has a function of diffracting the light of the polarization component of P polarization as 0th order light and the light of the polarization component of S polarization as 1st order light. Therefore, the P-polarized polarization component of the incident laser light is detected by the multi-segment photodetector 17, and the S-polarized polarization component of the incident laser beam is detected by the multi-segment photodetector 16.

FIG. 2 is a perspective view showing the polarization direction of the light beam in the first embodiment of the optical integrated circuit of the present invention. In this embodiment, as shown in the drawing, the aspherical objective lens 22 is used in advance.
The optical system is set so that the light emitted from is linearly polarized light, and the P polarized light component Ep and the S polarized light component Es have the same magnitude. Here, the electric field component having the Z-axis direction is the P-polarized component Ep, and the one having the X-axis direction is the S-polarized component Es. It is known that the light of the P-polarized component Ep and the light of the S-polarized component Es have a phase difference or a difference in the reflectance value depending on the incident angle of the light during total reflection.

Further, depending on the incident angle of the light beam on the hologram optical element and the thickness of the hologram, the P-polarized component E
It is known that a phase difference occurs between p and the S-polarized component Es, or a difference occurs in reflectance. Also, the semiconductor laser 1
It is known that the emitted light from 3 has a polarization component parallel to the active layer of the semiconductor laser 13 as a main component.

As shown in FIG. 2, the semiconductor laser 13 is mounted on a submount 12 having an inclined surface with an angle θ, and the laser light is attached while being rotated by an angle θ around the optical axis of the emitted light. , Aspherical objective lens 2
It is possible to change the ratio of the P-polarized component Ep and the S-polarized component Es of the light emitted from the light source 2. Therefore, by optimally designing the incident angle of the light beam, the thickness of the hologram, the mounting angle of the semiconductor laser 13, etc., the aspherical objective lens 22
It is possible to make the outgoing light from the linearly polarized light and to make the P polarized light component Ep and the S polarized light component Es equal in magnitude.

FIG. 3 shows the polarization direction of the reflected light from the magneto-optical disk. The light before entering the magneto-optical disk is shown in FIG.
As shown in (b), since the polarization direction is not rotated in either direction, the P polarization component Ep and the S polarization component Es are equal. However, the light reflected by the magneto-optical disk is shown in FIG.
As shown in (c), the polarization direction is rotated to ± 0.4 ° depending on the recorded information on the magneto-optical disk. The polarization direction is -0.4 due to the reflection on the magneto-optical disk.
When rotated by about 0 °, the P-polarized component Ep of the return light E becomes larger than the S-polarized component Es as shown in the left diagram of FIG. 3C. On the contrary, when rotated by about + 0.4 °, the S-polarized component Es of the return light E becomes larger than the P-polarized component Ep as shown in the right diagram of FIG. 3C. The polarization component at the time of actual reading is either the P polarization component Ep or the S polarization component Es.

In order to detect various polarized light components, when the return light E from the magneto-optical disk to the aspherical objective lens 22 is linearly polarized light and the P polarized light component Ep and the S polarized light component Es are equal to each other, multi-divided light detection is performed. The diffraction angles of the hologram beam splitter 18 and the hologram polarization beam splitter 15 and the thickness of the hologram are optimally designed so that the light intensities detected by the devices 16 and 17 become equal. Thereby, when the P-polarized component Ep of the return light E to the aspherical objective lens 22 is larger than the S-polarized component Es, the multi-segment photodetector 1
Similarly on 7 and 16, the P-polarized component Ep becomes larger.

Therefore, conversely, when the S polarization component Es is larger, the S polarization component Es is larger on the photodetector. P
By differentially detecting the light intensities detected by the polarization-detecting multi-segment photodetector 17 and the S-polarization detecting multi-segment photodetector 16, it is possible to determine in which direction the polarization direction is rotated. Based on this, the information signal of the magneto-optical disk can be reproduced.
Also, when playing a compact disc (CD),
It is possible to read the information signal from the sum of the light intensities detected by the two multi-divided photodetectors 17 and 16.

(Second Embodiment) FIG. 4 shows a second embodiment of the optical integrated circuit of the present invention. In this embodiment, first, the three-beam generating diffraction grating 41 and the aspherical objective lens 42 are provided on the upper surface 40a.
The transparent body 40 having is prepared by integral molding. The optical integrated circuit 30 uses the transparent body 40 as the optoelectronic integrated circuit board 31.
It is formed by pasting on. As the adhesive used for bonding, it is desirable to use an adhesive having optical characteristics such as a refractive index as close as possible to the optical characteristics of the transparent body 40.

In the optical integrated circuit 30 of this system, unlike the optical integrated circuit 10 of the first embodiment, the optoelectronic integrated circuit board 31 is used.
The transparent body 40 is not formed on the lower side. Therefore, if the optical integrated circuit 30 is used, the optical pickup can be thinned. The structure and operation principle of the optical integrated circuit 30 are exactly the same as those of the first embodiment. Therefore,
This part is given the same number as in the first embodiment, and a detailed description is omitted.

[0035]

According to the optical integrated circuit of the present invention, the optoelectronic integrated circuit substrate and the transparent body are integrated, and the returning light beam is separated into two kinds of linearly polarized light on the propagation light path of the light beam in the transparent substrate. An optical element is provided. As a result, it is possible to read the magneto-optical disk and realize an integrated optical integrated circuit having a polarization plane detection function.

In the optical pickup according to the second aspect, by integrating the optoelectronic integrated circuit substrate and the transparent body, the number of extra alignment steps can be reduced and the cost can be reduced. Further, it is possible to provide a compact and lightweight optical pickup for a magneto-optical disk.

In the optical information processing apparatus according to the third aspect, the diffraction angles of both beam splitters and the thickness of the hologram are optimally designed in order to detect various polarization components. When the P-polarized light component of the return light to the objective lens is larger than the S-polarized light component, the P-polarized light component is also larger on the multi-division photodetector. On the contrary, when the S-polarized component is larger, the S-polarized component is larger on the photodetector.

By differentially detecting the light intensities detected by the multi-segment photodetectors for P and S polarization detection, it is possible to determine which direction the polarization direction has rotated. Therefore, the information signal of the magneto-optical disk can be reproduced, and the information signal can be read from the sum of the light intensities detected by the two multi-divided photodetectors even when reproducing the CD.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of an optical integrated circuit of the present invention.

FIG. 2 is a perspective view showing a polarization direction of a light beam according to the first embodiment.

FIG. 3 is a diagram showing a polarization direction of reflected light from an optical disc.

FIG. 4 is a side view showing a second embodiment of the optical integrated circuit of the present invention.

FIG. 5 is a diagram showing an optical system of a conventional CD optical pickup.

6A and 6B are views showing a conventional optical integrated circuit for CD, in which FIG. 6A is a side view and FIG. 6B is a perspective view of an optoelectronic integrated circuit substrate.

FIG. 7 is a diagram showing an optical system of a conventional optical pickup for a magneto-optical disk.

[Explanation of symbols]

 10 30 optical integrated circuit 11, 31 optoelectronic integrated circuit substrate 12, 32 submount 13, 33 semiconductor laser 14, 34 monitor photodetector 15, 35 hologram polarization beam splitter 16, 36 multi-segment photodetector for S polarization detection 17 , 37 P multi-segment photodetector for polarization detection 18, 38 Hologram beam splitter 19, 39 Hologram collimator lens 20, 40 Transparent body 21, 41 3 Beam generation diffraction grating 22, 42 Aspherical objective lens

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiko Nakano 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture

Claims (3)

[Claims] 1. A laser element, a light receiving element, a control circuit for controlling each of the laser element and the light receiving element, a signal processing circuit, and an optoelectronic integrated circuit board on which various optical elements are integrated, and various optical elements are integrated on the surface. In an optical integrated circuit in which a transparentized body is integrally molded or bonded, the laser element emits toward the inside of the transparent body, the various optical elements on the surface of the transparent body, and the optoelectronic integrated circuit substrate. An optical integrated circuit having an optical element for separating a return light beam into two kinds of linearly polarized light on a path of a light beam propagating while reflecting between the above various optical elements. 2. A hologram polarization beam splitter in which the optical element diffracts the light of the P-polarized component of the return light beam as the 0th-order light and the light of the S-polarized component as the primary light, and the P-polarized component and the S-polarized light. An optical pickup equipped with an optical integrated circuit having a multi-segment photodetector that detects component light and photoelectrically converts it. 3. A beam splitter and a hologram in which the optical element is optimally designed in terms of diffraction angle and thickness so that the detection light intensities of two types of linearly polarized light are equal, and when the polarization direction of the return light beam is rotated, Multi-split photodetectors for P-polarization detection and S-polarization detection that determine the rotation of the polarization direction by differentially detecting the light intensity of a certain kind of linearly polarized light, and both polarizations detected by the multi-split photodetector An optical information processing apparatus equipped with an optical integrated circuit having an information regenerator that differentially detects the light intensity of components and reproduces an information signal of a magneto-optical disk.