JPH01273252A - Magneto-optical pickup - Google Patents

Abstract

PURPOSE:To reduce the size and weight of a magneto-optical pickup and, at the same time, to cause the pickup to make high-speed access and high-speed transfer by making the optical system of the pickup smaller in size by using optical waveguides and uniting a magnetic circuit and optical circuit to one body. CONSTITUTION:In an optical modulation system, recording is performed by impressing an auxiliary magnetic field upon a magneto-optical disk 21 from the magnetic gap (g) of the magnetic circuit 28 and making the recording light of a laser diode 36 to incident on the disk through an optical waveguide 38 at the time of recording. In a magnetic field modulation system, on the contrary, recording is performed by making the recording light of a laser diode 30 incident on the disk 21 through the optical waveguide 38 and impressing a magnetic field corresponding to recording signals upon the disk 21 from the magnetic gap (g) of the magnetic circuit 28 by inputting the recording signals to the circuit 28. At the time of reproduction, reproducing light from the diode 36 is made incident on the disk 21 through the waveguide 38 and the reflected light rays from the disk 21 are detected by a photodetector 37 through another optical waveguide 40.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optic pickup for magneto-optical recording.

(Summary of the Invention) The present invention provides a magneto-optical pickup for magneto-optical recording that includes a magnetic circuit having an air gap, a winding that excites the magnetic circuit, and a magnetic circuit that allows at least recording light to pass through the air gap in the magnetic circuit for magnetic recording. By constructing an optical waveguide that guides the medium, it can be made smaller and lighter, and can support high-speed access, high-speed transfer, etc.

[Conventional technology]

FIG. 9 shows an example of a conventional magneto-optical disk for a magneto-optical disk. In the figure, (1) shows a magneto-optical disk which is a recording medium, and (2) shows a laser light source. The light beam from the laser beam 5 (2) passes through the grating (3) and the lens system (4).
, a polarizer (5), a beam splinter (6), and an objective lens (7), the light is focused onto the magneto-optical disk (1).

The returning light beam reflected from the magneto-optical disk +11 is reflected by the beam splinter (6) in the direction of 1/2
After passing through a wavelength plate (8), differential detection is performed by a polarizing beam splitter (9) and photodiodes (10) and (11) to obtain a reproduced signal. Note that (12) and (13)
is a cylindrical lens.

On the other hand, when recording, a light beam is irradiated so as to be focused on the recording layer of the magneto-optical disk (11) using magneto-optic pink-up, and a recording magnetic field is That is, in the optical modulation method, an auxiliary magnetic field is applied, and in the magnetic field modulation method, a signal magnetic field is applied.

[Problems to be Solved by the Invention] However, in the conventional magneto-optical pink amplifier described above, the structure is large due to the use of optical lens threads, and the recording magnetic field is transferred to the magneto-optical disk by a magnet or coil. Since the voltage is applied from the back side, there are drawbacks such as a complicated mechanism, making high-speed access and heavy-speed transfer difficult.

In view of the above points, the present invention provides a magneto-optical pickup that is small, lightweight, and capable of high-speed access and high-speed transfer at IM@.

(Means for Solving the Problems) The magneto-optical pickup of the present invention has a magnetic recording medium (21
), a winding (29) that excites the magnetic l path (28), and a magnetic circuit (28) having a gap g facing the magnetic circuit (28); It has a guiding optical waveguide (31).

The magneto-optical pickup of the present invention can be configured as a recording/reproducing head, or can be configured exclusively for a recording head. When used as a recording/reproduction head, the optical waveguide (31) is configured to guide recording light and reproduction light. A light source (36) and a photodetector (37) are arranged in the optical waveguide (31). Further, the optical waveguide (31) when used exclusively for the recording head is configured to guide only the recording light, and a light source (36) is arranged at the end of the optical waveguide.

[Effect]

According to the above configuration, when recording, the optical waveguide (3
1), the recording light is irradiated onto the magnetic recording medium (21), and the magnetic recording medium (21) is
Apply a recording magnetic field to. In this case, in the optical modulation method, a Jji 1IIJ magnetic field is provided by the magnetic circuit (28), and in the magnetic field modulation method, a magnetic field based on the recording signal is provided by the magnetic circuit.

Furthermore, when configured as a recording/reproducing head, recording is performed as described above. During playback, the optical waveguide (31)
The reproduction light is incident on the magnetic recording medium (21) through the optical waveguide (3), and the reflected light is received by the photodetector (37) from which the reproduction signal is extracted.

The above-mentioned magneto-optical big amplifier uses an optical waveguide (31) instead of the conventional large lens thread, and the optical system is made smaller. By combining them together, a recording head for magneto-optical recording or a recording/reproducing head can be made smaller and lighter, and can be formed on a slider with nJ capability, allowing high-speed access and heavy-speed transfer.

[Example] Hereinafter, an 8% example of the magneto-optical pick amplifier according to the present invention will be described with reference to the drawings.

FIGS. 1 and 2 show an example of the magneto-optical pickup of the present invention. In FIGS. 1 and 2, (21) is a magnetic recording medium, such as a magneto-optical disk having a recording 7-(23) on a substrate (22), and (24) is a slider, the end surface (24A ) is formed with a magneto-optical pickup (25) according to the present invention.

As shown in Fig. 2, the magneto-optical pink-up (25) consists of a ferrite substrate (26) (the slider (24) can also be moved) and a substantially U-shaped ferrite core (27).
) and a magnetic circuit (28) constituting a closed magnetic path formed by a magnetic air PJ (31) at the tip facing the magneto-optical disk (21), and a ferrite core (27) for exciting this magnetic circuit (28). The winding (29) wound on the ferrite substrate (26) is
(30) and an optical circuit (32) including an optical waveguide (31) which is disposed through a magnetic gap g and faces a magneto-optical disk (21).

This optical circuit (32) is formed as follows.

For example, in the examples shown in FIGS. 3 and 4, a semiconductor laser diode (36) serving as a light source is placed on a substrate (26) via an insulator 71 (30), and a photodetector (37) made of, for example, a photodiode is installed at one end. is in contact with or faces the laser diode (36), and the other end faces the magneto-optical disk (21), so that the light emitted from the laser diode (36) is directly incident on the music on the magneto-optical disk (21). optical waveguide (
38) and this first optical waveguide (38) constitute a cross-type optical directional coupler (39), and the reflected light from the magneto-optical disk (21) is transmitted from the first optical waveguide (38) to a cross-type optical directional coupler (39). A second optical waveguide (40) is provided which leads to a photodetector (37) via a directional coupler (39). A laser diode is used.The first and second optical waveguides (38) and (40) are made of, for example, soda glass, respectively.
It is constructed of an ion-exchange waveguide by exchanging one ion and Ha+ ion after immersing the seed in the NO]i-volume melt, or a Ti-diffused LiNb0i special waveguide formed by i'i diffusion into a LiNb0i crystal, for example. On the other hand, although the laser diode (36) is linearly polarized light with a polarization ratio of 1-1, the laser diode (36) in the first optical waveguide (3B) and the crossed optical direction are used to maximize the re-outgoing signal. Optical detection W (37) on the way between the optical couplers (39) and the second optical waveguide (40)
A metal Talarad type mode filter (which becomes a polarizer and an analyzer, respectively) is installed between the
46) and (4?) are provided. These metal clad type mode filters (46) and (47) are shown in FIG. 5 (cross-sectional view taken along line A-A in FIG. 3) and FIG. 6 (curved view taken along line B-8 in FIG. 3). A metal layer (50) such as A1 is placed on the first optical waveguide (38) and the second optical waveguide (40) via buffer layers (48) and (49) made of an insulating layer such as 5iOz, respectively. , (51) are deposited and formed. The angle between the metal clad mode filter (46) serving as a polarizer and the metal clad mode filter (4'?) serving as an analyzer is 45.
As shown in FIGS. 4 and 5, the buffer layer (4B) is formed at a predetermined angle close to 45° or 45°, respectively.
(49) Kim Mile (50), (51)'
c angle cX, angle 1jM++- (formation L, then α + β =
The angle is #45° or α+β+45°. FIG. 6 (a cross-sectional view taken along line C-C in FIG. 3) shows a cross-section of the cross-type optical directional coupler (39), and this optical circuit (32).
Then, the emitted light from the laser diode (36) enters the first optical waveguide (38), propagates through the metal craft mode filter (46), which is a polarizer, and is directed to the magneto-optical disk (31).
) is incident on the plane. Magneto-optical disk during playback (31)
The reflected light passes through the metal clad mode filter (47) of the analyzer and is detected! The light is received by (37),
A reproduced signal is extracted from this.

7 and 8 show 41 examples of the optical circuit (32).

In this example, one end is t facing the magneto-optical disk (21).
A first optical waveguide (38) with a laser diode (36) arranged at the h end, and one end adjacent to one end of the first optical waveguide (38) and a cross-sectional area of one end of the first optical waveguide (38). It consists of a second optical waveguide (40) having a wider area and a photodetector (37) arranged at the other end, and each optical waveguide (3
B) In the middle of (40), metal clad mode filters (46) and (47) serving as a polarizer and analyzer similar to those explained in FIGS. 4 and 5 are provided. This optical circuit (32) can achieve a narrow trunk, improve reproduction output, suppress the influence of returned light, and prevent unstable oscillation of the laser diode (36).

In addition, the optical circuit (32) has the configuration shown in FIGS.
) is also possible. Furthermore, optical circuit (32)
As shown in the figure, a branched optical waveguide is provided, a part of which faces the magneto-optical disk (21), a laser diode (3ti) is arranged at the end of one branched waveguide Li, and the other branched waveguide It is also possible to have a configuration in which a photodetector (37) is arranged at the end.

Incidentally, in place of the insulating layer (30) in FIG. 2, for example, a silicon substrate is used, and the photodetector 13 (37) of the photodiode is built into this silicon substrate, and the laser diode (36) and the above-mentioned are formed on this silicon substrate. optical waveguide (31)
It can also be configured to place .

Next, the operation of the magneto-optical pickup (25) having such a configuration will be explained.

During recording, for example, in the optical modulation method, the magnetic circuit (28)
An auxiliary magnetic field is applied to the magneto-optical disk (21) from the magnetic air Bg of
Inject it into the camera and record it.

In the magnetic field modulation method, recording light from a laser diode (30) passes through a first optical waveguide (38) to a magneto-optical disk (
21), a recording signal is input to the magnetic circuit (28), and a magnetic field corresponding to the recording signal is applied to the magneto-optical disk (21) through the magnetic gap g to perform recording.

When playing next time, use the laser diode 1 as described above.
- The reproduction light from (36) is incident on the magneto-optical disk (21) through the first optical waveguide (38), and the reflected light is detected by the photodetector (37) through the second optical waveguide (40). An exogenous signal is extracted from this.

According to the magneto-optical pickup (25) having such a configuration,
While reducing the size of the optical system using the optical waveguide (31),
By configuring this by integrating the magnetic circuit (28) and the optical circuit (32) in which the winding (29) is arranged so as to pass through the magnetic gap g, it is possible to achieve so-called recording for compact and lightweight magneto-optical recording. , reproduction-soto is obtained. In other words, this magneto-optical pink amplifier can be formed on a slider, achieving universal access and high-speed transfer. Furthermore, the magnetic circuit (28)
Recording and reproduction are performed by making the recording light incident on the optical magnetic disk (21) through the same first light 2F# wave path (38) provided through the magnetic gap g, so that recording and reproducing are performed. There is no need to align the trunk of the raw head. Furthermore, it can be provided at a lower cost than a magneto-optical pickup using a conventional optical lens system.

The upper part was used for a magneto-optical pickup for recording and reproducing, but there is also an optical circuit (31) consisting of a laser diode (36) and an optical waveguide (3B) that passes only the recording light.
It is possible to configure a magneto-optical pink-up that performs only recording by configuring .

〔Effect of the invention〕

According to the present invention described above, a magnetic circuit having an air gap facing a magnetic recording medium, a winding that excites the magnetic circuit, and an optical waveguide that guides at least recording light to the magnetic recording medium through the air gap. By configuring the magneto-optical pickup for recording, or for recording and reproducing, it is possible to form a compact and lightweight magneto-optical pickup.

Therefore, this magneto-optical pickup can be formed on a slider, and high-speed access and high-speed transfer can be achieved.

Furthermore, it can be provided at a lower cost than a conventional magneto-optical pickup using an optical lens system.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing an example of a magneto-optical pickup according to the present invention arranged on a slider, Figure 2 is a diagram showing an example of a magneto-optic pickup according to the present invention, and Figure 3 is a diagram showing an example of an optical circuit according to the present invention. A plan view showing an example, and FIGS. 4 to 6 are sectional views taken along the line A-A, a sectional view taken along the line B-13, a sectional view taken along the line C-C, and FIGS. 7 and 8, respectively. A plan view showing another example of the optical circuit and a perspective view of the main part of the tip thereof, No. 9
The figure is a configuration diagram showing an example of a conventional magneto-optic pick amplifier. (21) is a magneto-optical disk, (25) is a magneto-optical pickup, (26) is a ferrite substrate, (2''/) is a ferrite core, (28) is a magnetic circuit, (29) is a winding wire, (
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Claims (1)

[Claims] A magneto-optical pickup comprising: a magnetic circuit having an air gap facing a magnetic recording medium; a winding that excites the magnetic circuit; and an optical waveguide that guides at least recording light to the magnetic recording medium through the air gap.