JPH0198136A - Hybrid optical element - Google Patents

Abstract

PURPOSE:To closely arrange an LD and a photodetector and to simplify a device by storing a light source and the photodetector in the same package to constitute one hybrid optical element. CONSTITUTION:An LD1 and a photodetector 10 are arranged on a block for heat radiation and are constituted in one package. The light beam emitted from the LD1 is condensed on an optical disk 6 through a beam splitter 4 and a condenser lens 5. The reflected light goes reverse to be made incident on the photodetector 10 through the beam splitter 4.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a hybrid optical element, particularly a hybrid optical device applied to an optical head device used for recording/reproducing information on an optical sensor or an optical information recording medium. It is related to the element.

[Prior Art] FIG. 6 shows the configuration of a conventional optical head device. In the figure, (1) is a semiconductor laser (hereinafter referred to as LD) that is a laser light source, (2) is the emitted light flux of LD, and (4
) is a flat beam splitter, (5) is a condensing lens, (
6) is an optical information storage medium (hereinafter referred to as an optical disk),
(7) is a pit which is information recorded on the optical disk (6), and (10) is a photodetector.

The planar beam splitter (4) is LD (
The emitted light beam (2) of 1) is reflected on the first surface (4a) and enters the condenser lens, while the light reflected by the information surface of the optical disk (6) is transmitted through the first surface. This is a spectroscopic element that reflects the light on its second surface and makes it incident on the photodetector (10).

The conventional optical head device has the above configuration, and its operation will be explained below.

The light beam (2) emitted from the LD (1) is reflected by the first surface (4a) of the beam splitter (4), and then is directed onto the information track surface of the optical disk (6) by the condenser lens (5). The light is focused.

The light focused on the optical disk (6) is reflected by the information track surface, passes through the condensing lens (5) again, and then passes through the first surface (4a) of the beam splitter (4).
Furthermore, after being reflected by the second surface (4b) of the beam splitter (4), it passes through the first surface (4a) again. Therefore, the reflected light beam reflected from the beam splitter (4) is given astigmatism, that is, an aberration that forms separate focal lines for meridian rays and spherical rays, as is well known, and this reflected light beam is The light is incident on the detector (10).

Here, the first surface (4a) and the second surface (4b) of the beam splitter (4) are parallel, and the angle of incidence on the first surface (4a) with thickness t1 refractive index n1 is θ (rad). Then, the astigmatism difference Δ is expressed by the following equation.

(n 1) △-2×t×θ2×□...(1) , 13 The reflected light flux (2') from the beam splitter (4) given the astigmatism is the output of the LD (1) Luminous flux (2)
The chief ray, which travels parallel to and in the opposite direction to that and is shown by a dashed line in the figure, is 2・t-tanθ * cos
The light is incident on the photodetector (10) with a deviation of θ. Here, the θ'' satisfies n-5inθ−sinθ.

In such an optical head device, a photodetector (1
0) is the luminous flux reflected from the disc when the condensed spot on the optical disc (6) is in focus, as shown in Figure 6(b).
As shown in , it is placed at a position in the optical axis direction that provides the circle of least confusion (11).

And, as shown in the figure, this photodetector (10)
Detection parts (10a), (10b), (10c), (10d
), and each of these detection units detects the amount of incident light flux.

As is well known, the output of each of these detection units is the sum of the outputs of the detection units facing each other in the diagonal direction, since the spot on the photodetector (10) becomes a distorted spot (12) when a defocus occurs. By calculating the difference output between the pair of opposing detection units, the defocus of the light beam can be detected.

That is, the opposing detection unit pair is ((10a) +10c)l −1(10b) +
(10d)l, and this calculated output signal is output as a focus error signal, and the focus shift of the light spot on the optical disk is corrected by an ocus actuator (not shown).

The defocus detection method in this case is the astigmatism method, and the 6th
As shown in Figure (b), when the spot on the optical disk is in the focused state (11), it becomes a circle of least confusion and becomes approximately circular, but as the distance between the head device and the optical disk (6) changes, When the defocus caused by the photodetector (10
) is transformed into a vertically long and horizontally long oval shape as shown by the broken line. Therefore, by electrically detecting the deformed ellipse, the focal position shift can be detected.

[Problems to be Solved by the Invention] Since the conventional optical head device is configured as described above, the LD (1) and the photodetector (10) are placed close to each other, and the head is small. Although this is advantageous in terms of integration, there is a problem in that conventional LD packages and photodetector packages cannot be used because they are too close together.

As an example of the configuration of a typical optical head device, the lateral magnification of the condenser lens (5) is 115, and the surface runout of the optical disk (6) is focus-controlled and the near control range is 10 μm.
Then, the required astigmatism difference Δ is 500 μm.

At this time, from equation (1), if θ-45° and n-1,5, then a flat beam splitter (4) with t=1.1m11+ will be used.

From the above, the principal ray (2) of the emitted luminous flux and the principal ray (2) of the reflected luminous flux are
2″) has a deviation of only 0.83 mm.

On the other hand, the external dimensions of conventional LD packages and photodetector packages are several mm or more, and as mentioned above,
It was difficult to arrange two packages in a space smaller than l11.

In order to solve the above problems, it is an object of the present invention to obtain a hybrid optical device in which an LD and a photodetector are arranged close to each other.

[Means for solving the problem] In order to achieve the above object, a semiconductor laser chip and a photodetector semiconductor chip are attached to a heat dissipation block of the semiconductor laser chip, and housed in the same package as one hybrid optical device. This is an application of our method to an optical head device.

[Function] According to the present invention, the light source and the photodetector can be arranged in close proximity of 1 mm or less, and the configuration of the optical head device can be simplified.

[Embodiments] Hereinafter, preferred embodiments of the hybrid optical device according to the present invention will be described with reference to the drawings.

FIG. 1 shows an optical path of an optical head device to which a first embodiment of the hybrid optical device according to the present invention is applied, and the same parts as in the conventional example in FIG. 6 are given the same reference numerals. The explanation will be omitted.

In FIG. 1, (8) is a heat radiation block, (9) is a stem, and (13) is a lead.

The LD (1) and the photodetector (10) are each in the form of a semiconductor chip.゛The features of the present invention are that the conventional LD (1), photodetector (
Reference numeral 10) is a hybrid optical device (14) in which two optical devices, which were each configured in separate packages, are configured in one package.

Here, the configuration of the hybrid optical element (14) will be explained in detail using FIG. 2.

The heat dissipation block (8) is made of a highly thermally conductive material such as silver or copper, and is attached to or integrally formed with the stem (9). LD (1) is a semiconductor laser chip, and is attached to the side surface of the heat dissipation block (8) via a silicon submount (18).

The emitted light beam (2) is emitted perpendicularly to the stem (9) as shown in the figure, and its power is measured by the monitoring photodetector (16).
) is detected.

On the other hand, the photodetector (10) is PIN-photo.

The LD (1
) The mounting is perpendicular to the surface, and is mounted on the surface facing the laser beam emission direction via an insulating plate (17).

In this embodiment, the photodetector (10) is bonded to the photodetector (10) via an insulating material, such as a ceramic plate, to electrically isolate the photodetector (1o) from the heat dissipation block (8). Therefore, a reverse bias voltage can be applied to the photodetector (10) independently of the LD (1), and a photocurrent can be extracted.

In this embodiment, the photodetector (10) consists of a six-divided detector as shown in FIG. 2(c). The center quadrant detector is for reading out signals and detecting the astigmatic focus error signal as described above.

The two outer detectors are for obtaining a tracking error signal. For example, when the well-known twin spot method is used, the beam splitter surface (4a) shown in Fig. 1 can be applied to this embodiment. If a reflection type diffraction grating is formed on the surface, there is no need to use new parts.

Further, the photodetector (10) is also formed with an electrode (3) for extracting the photocurrent of each detector.

On the other hand, several leads (13) are hermetically inserted into the stem (9) as shown in FIG. 2(b) (a top view of FIG. 2(a)), and the photodetector ( The electrode (3) of 10) and the chip of LD (1) are wire-bonded to the monitoring detector (16), respectively.

In particular, in this embodiment, the bonding pad portion at the top of the lead (13) faces in the same direction as the photodetector (10) surface, making wire bonding work easy.

Furthermore, since only one lead is drawn in Figure 2(a),
It is preferable to match the height of each head to the height of the electrode (3).

If such a hybrid optical element (14) is used, even if the emitted light beam (2) and the reflected light beam (2') are close to each other at a distance of 1 mm or less, the light [(1) and the photodetector (18) can be connected to the semiconductor chip state. Since they can be placed close to each other, an optical head device using a conventional optical path can be constructed.

Next, a second embodiment of the present invention will be described using FIG. 3.

The second embodiment is an example in which a flat plate beam splitter (4) as a light separation element is also housed in a hybrid optical element (14).

The flat beam splitter (4) is fixedly attached to a base (20) formed integrally with the stem (9). In this configuration, the light beam emitted from the hybrid optical element (14) is bent by 90 degrees compared to the first embodiment.

The other configurations are exactly the same as those of the first embodiment, and have the same effects. In the second embodiment, the optical head device has only two optical parts, a condenser lens and a hybrid optical element, and the device can be made smaller and simpler.

In the first and second embodiments above, only an optical head device using a parallel plate beam splitter using a hybrid optical device as a light separation means was shown, but the hybrid optical device of the present invention uses a light source and a photodetector in close proximity. Since the present invention is arranged in such a manner that the light beam is separated, the same effect can be obtained even when applied to an optical head device using a holographic element as a light separation means.

Hereinafter, as a third embodiment, an example of application of the hybrid optical element according to the present invention to an optical head device using a holographic element as a light separating means will be described.

In FIG. 4, (4) is a holographic beam splitter, which functions to separate a reflected beam (2'') forming a small angle θ from an output beam (2).

Therefore, by using the hybrid optical element (14) shown in FIG. 2, it is possible to provide an optical head device with a simple configuration.

Furthermore, if the holographic element (4) is formed on the window glass (19) in FIG. 2, a simpler configuration can be achieved.

If the hybrid optical element (14) is used, each diffraction angle θ of the holographic element (14) can be made very small, so the grating period can be large, and the holographic element can be manufactured easily.

Furthermore, although the first, second, and third embodiments described above show examples of application of the hybrid optical device to an optical head device, it can also be applied to, for example, a position sensor and a surface roughness meter, as shown in FIG. As shown, by scanning the material (21) in six directions, the surface shape of the material can be calculated from the focus error signal in the form of the amount of deviation from the focal point of the condensing lens (5).

[Effects of the Invention] As described above, according to the present invention, a light source and a photodetector are housed in the same package to form one hybrid optical element, which reduces the number of parts in an optical head device and improves the optical path configuration. It can be simplified and downsized.

[Brief explanation of the drawing]

FIG. 1 is an optical path diagram of an optical head device to which the first embodiment of the hybrid optical device according to the present invention is applied, FIG. 2 is a block diagram of the hybrid optical device according to the first embodiment, and FIG. FIG. 4 is a block diagram of a second embodiment of the hybrid optical device according to the present invention, FIG. 4 is an optical path diagram of an optical head device to which the third embodiment of the hybrid optical device according to the present invention is applied, and FIG. FIG. 6, which is an explanatory diagram of an example of the application of the optical sensor, is an optical path diagram of a conventional optical head device. In the figure, (1) is a light source, (4) is a light separation element, and (5) is a light source.
) is a condenser lens, (6) is an optical disk, (8) is a heat dissipation block, (10) is a photodetector, (13) is a lead, (
14) is a hybrid optical device. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Patent attorney Masuo Oiwa (and 2 others) Figure 1 i: LD 4: Beam spritzer 8: Heat dissipation block 9: Stem 10: Photodetector 13: Lead 14: Hybrid optical device Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 (b) Procedural amendment (voluntary) 2. Name of the invention Hybrid optical device 3. Person making the amendment Representative Moriya Shiki 4. Agent 5. Details subject to amendment claims and detailed description of the invention. 6. Contents of Correction Claims (1) A laser light source that emits a laser beam, a condensing lens system that condenses the laser beam onto an optical information recording carrier, and a condensing lens system disposed in the condensing lens system that It is applied to an optical head device including a light component I4'ri that separates a laser beam and a light reflected from the record carrier, and a photodetector that receives the light reflected from the information record carrier, and the photodetector is attached to one side of a heat dissipation block to which the light source is attached, and the light source and the photodetector are housed in the same package. (2) The hybrid optical device according to claim (1), wherein the photodetector is made of a pin semiconductor chip and is bonded to one surface of the heat dissipation block via an insulating key. . (3) A patent characterized in that the photodetector is mounted on the heat dissipation block, the light source is mounted substantially perpendicular to the surface, and the light source is mounted on the surface in the direction of the light emitted from the light source. A hybrid optical device according to claim (1) or (2). (4) The hybrid optical device according to any one of claims (1) to (3), wherein the hybrid optical device is hermetically isolated from outside air through a glass window. (5) The heat radiation block is attached to a stem having a plurality of electrode leads, and the electrode pads of the photodetector and the bonding pads of the leads are arranged on the same plane or parallel planes. A hybrid optical device according to the ranges (1), (2), and (3). (6) The hybrid optical device according to claims (1), (2), and (3), wherein the package also houses the light separation means. (7) The hybrid optical device according to claim (1), wherein the light separation means is a parallel plate beam splitter. (8) The hybrid optical device according to claim (1), wherein the light separation means is a holographic device. (9) The hybrid optical device according to claim (4) or (8), wherein the holographic element is formed on the window glass.

Claims (9)

[Claims] (1) A laser light source that emits a laser beam, a condensing lens system that condenses the laser beam onto an optical information recording carrier, and a condensing lens system that is arranged in the condensing lens system to emit the laser beam and reflected light from the recording carrier. and a photodetector that receives reflected light from the information recording carrier, and the photodetector is connected to a heat dissipation block to which the light source is attached. A hybrid optical device, characterized in that the light source and the photodetector are mounted on one surface and housed in the same package. (2) The hybrid optical device according to claim (1), wherein the photodetector is made of a pin semiconductor chip and is bonded to one surface of the heat dissipation block via an insulating material. . (3) A patent claim characterized in that the photodetector is attached to a surface of the heat dissipation block that is substantially perpendicular to the mounting surface of the light source and that faces in the direction of the light emitted from the light source. The hybrid optical device according to the range (1) or (2). (4) The hybrid optical device according to any one of claims (1) to (3), wherein the hybrid optical device is hermetically isolated from outside air through a glass window. (5) The heat radiation block is attached to a stem having a plurality of electrode leads, and the electrode pads of the photodetector and the bonding pads of the leads are arranged on the same plane or parallel planes. A hybrid optical device according to the ranges (1), (2), and (3). (6) The hybrid optical device according to claims (1), (2), and (3), wherein the package also houses the light separation means. (7) The hybrid optical device according to claim (1), wherein the light separation means is a parallel plate beam splitter. (8) The hybrid optical device according to claim (2), wherein the light separation means is a holographic device. (9) The hybrid optical device according to claim (4) or (8), wherein the holographic element is formed on the window glass.