JP2009004006A - Optical assist magnetic recording head, optical assist magnetic recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical assist magnetic recording head in which use efficiency of light is high and thickness is thin, and an optical assist magnetic recording device. <P>SOLUTION: The optical assist magnetic recording head performs information recording for a recording medium using light. The head has a slider moving relatively for the recording medium, and an optical waveguide guiding light from a light source to the slider. The optical waveguide has a core waveguide which is formed in a L-shape and propagates light, a slant reflecting light propagated from the light source and guiding it to the slider is formed at a bent part of the L-shape of the core waveguide. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an optically assisted magnetic recording head and an optically assisted magnetic recording apparatus.

  In the magnetic recording method, when the recording density increases, the magnetic bit is significantly affected by the external temperature and the like. For this reason, a recording medium having a high coercive force is required. However, when such a recording medium is used, the magnetic field required for recording also increases. The upper limit of the magnetic field generated by the recording head is determined by the saturation magnetic flux density, but its value approaches the material limit and cannot be expected to increase dramatically. Therefore, a method of guaranteeing the stability of the recorded magnetic bit by locally heating at the time of recording, causing magnetic softening, recording with a reduced coercive force, and then stopping the heating and naturally cooling Has been proposed. This method is called a heat-assisted magnetic recording method.

  In the heat-assisted magnetic recording method, it is desirable to instantaneously heat the recording medium. Further, the heating mechanism and the recording medium are not allowed to contact each other. For this reason, heating is generally performed using absorption of light, and a method using light for heating is called a light assist method.

  In the optically assisted magnetic recording system, a magnetic recording unit that reads and writes information on a recording medium, a magnetic reproducing unit, etc., a slider that floats and moves relative to the recording medium, an optical fiber that couples light from a light source, and an optical fiber Various optically assisted magnetic recording heads having an optical element or the like for deflecting the emitted light and guiding it to a slider have been proposed.

For example, an optical element composed of a prism and a transparent dielectric is provided at the tip of the slider, and the light guided from the light source via the optical fiber is deflected by 90 degrees by the prism and provided on the surface facing the recording medium of the transparent dielectric. An optically assisted magnetic recording head configured to guide light to a plasmon probe is known (see Patent Document 1).
JP 2002-298302 A

  Incidentally, in recent years, with the progress of high-density information recording in a recording apparatus such as an HDD (Hard Disk Drive), for example, it is desired to reduce the size of a head that performs reproduction recording and the size of a slider that constitutes the head. The size of the slider is standardized as an International Disk Drive Association and Materials Association (IDEMA) standard. In order of size, they are named mini slider, micro slider, nano slider, pico slider, and femto slider. Among these sliders, the sliders currently attracting attention from the viewpoint of size are the nano slider, pico slider, and femto slider. Table 1 shows the size (size) and mass of these sliders.

  In high-density information recording, as can be seen from the size of the slider described above, not only the information on one disk is increased in density, but also the disks are arranged in multiple layers or housed in as small a housing as possible. It is also necessary to increase the spatial density. For example, assuming a multi-layer disk arrangement, the distance between the disks is required to be as small as possible, and the thickness of the optical head including the slider thickness shown in Table 1 should be about 1.5 mm or less. It is rare.

  However, the optically assisted magnetic recording head described in Patent Document 1 deflects the light emitted from the optical fiber using a prism and guides it to the slider. From the manufacturing method of this prism that is usually used, it is assumed that the thickness of the optical system excluding the slider needs to be about several hundred μm. For this reason, there is a problem that the thinning of the optical head is hindered.

  The optically assisted magnetic recording head described in Patent Document 1 is configured such that light emitted from an optical fiber is reflected by a prism, passes through a transparent dielectric block, and irradiates near the gap of a plasmon probe. In this case, the light emitted from the optical fiber spreads by diffraction before reaching the vicinity of the gap of the recording element, and there is a problem that the utilization efficiency of light contributing to the generation of near-field light near the gap is reduced. .

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an optically assisted magnetic recording head and an optically assisted magnetic recording apparatus that have high light utilization efficiency and are thin.

  The above object is achieved by the invention described in any one of 1 to 5 below.

1. In an optically assisted magnetic recording head that records information using light on a recording medium,
A slider that moves relative to the recording medium;
An optical waveguide for guiding light from a light source to the slider,
The optical waveguide has a core waveguide that propagates light formed in an L shape,
An optically assisted magnetic recording head, wherein an inclined surface that reflects light propagated from the light source and guides it to the slider is formed at an L-shaped bent portion of the core waveguide.

2. The core waveguide is bent at an angle of approximately 90 degrees and formed in an L shape,
2. The optically assisted magnetic recording head as described in 1 above, wherein the inclined surface is formed at an angle of approximately 45 degrees with respect to the optical axis of the core waveguide.

3. The slider is formed with a groove,
3. The optically assisted magnetic recording head as described in 1 or 2 above, wherein the optical waveguide is embedded in the groove.

4). A wall is formed at one end of the groove,
4. The optically assisted magnetic recording head as described in 3 above, wherein one end of the optical waveguide is in contact with a wall formed in the groove.

5). 5. The optically assisted magnetic recording head according to any one of 1 to 4,
And a recording medium on which information is recorded by the optically assisted magnetic recording head.

  According to the present invention, the optical waveguide has a core waveguide that propagates light formed in an L shape, and the L-shaped bent portion of the core waveguide is provided with a slope, and propagated from the light source on the slope. The light is reflected and guided to the slider. That is, the light from the light source is reflected while being confined in the core waveguide and guided to the slider. Therefore, an optical system such as a lens for condensing light at a predetermined position of the slider is not required, and the optically assisted magnetic recording head can be thinned. Moreover, the spread of light can be suppressed and the light utilization efficiency can be increased.

Embodiments of an optically assisted magnetic recording head and an optically assisted magnetic recording apparatus according to the present invention will be described below with reference to the drawings. In addition, although this invention is demonstrated based on embodiment of illustration, this invention is not limited to this embodiment. In addition, the same or corresponding parts in the embodiments are denoted by the same reference numerals, and repeated description is appropriately omitted.
Embodiment 1
FIG. 1 shows a schematic configuration of an optically assisted magnetic recording device (for example, a hard disk device) equipped with an optically assisted magnetic recording head (hereinafter also referred to as an optical head) according to Embodiment 1 of the present invention.

  The optically assisted magnetic recording apparatus 1A includes a recording disk (magnetic recording medium) 2, a suspension 4 that is rotatably provided in the direction of arrow A (tracking direction) with a support shaft 5 as a fulcrum, and a tracking attached to the suspension 4. Actuator 6, an optical head 3 attached to the tip of suspension 4, and a motor (not shown) that rotates disk 2 in the direction of arrow B are provided in housing 1. It can be moved relatively while floating.

  FIG. 2 is a cross-sectional view showing the configuration of the optical head 3. The optical head 3 is an optical head that uses light for recording information on the disk 2. The optical head 3 includes an optical fiber 11 that guides light from a light source (not shown) to the optical head 3, an optical waveguide 16 that functions as a light assist unit for spot-heating a recording portion of the disk 2 with laser light, and an optical fiber 11. An optical waveguide 12 that guides the emitted laser light LD 1 to the optical waveguide 16, a magnetic recording unit 17 that writes magnetic information to the optical waveguide 16, the recorded portion of the disk 2, and the disk 2. A slider 15 having a magnetic reproducing unit 18 for reading the magnetic information. The optical waveguide 12 is provided with a core waveguide 12a (not shown) that propagates the laser light LD1 from the optical fiber 11 and guides it to the optical waveguide 16.

  In FIG. 2, the magnetic reproducing section 18, the optical waveguide 16, and the magnetic recording section 17 are arranged in this order from the entry side to the withdrawal side (← direction in the figure) of the recording area of the disk 2. Not exclusively. Since the magnetic recording unit 17 only needs to be positioned immediately after the exit side of the optical waveguide 16, for example, the optical waveguide 16, the magnetic recording unit 17, and the magnetic reproducing unit 18 may be arranged in this order.

  The light guided by the optical fiber 11 is, for example, light emitted from a semiconductor laser. The laser beam LD1 emitted from the end face of the optical fiber 11 is condensed on the upper surface of the optical waveguide 16 provided in the slider 15 by the core waveguide 12a provided in the optical waveguide 12, and the optical waveguide 16 constituting this optical assist portion. Is emitted from the optical head 3 toward the disk 2.

The slider 15 moves relative to the disk 2 which is a magnetic recording medium while flying, but there is a possibility of contact if there is dust attached to the medium or a defect in the medium. In order to reduce wear generated in that case, it is desirable to use a hard material having high wear resistance as the material of the slider 15. For example, a ceramic material containing Al ₂ O ₃ , such as AlTiC, zirconia, TiN, or the like may be used. Further, as a wear prevention treatment, a surface treatment may be performed on the surface of the slider 15 on the disk 2 side in order to increase wear resistance. For example, when a DLC (Diamond Like Carbon) film is used, the light transmittance is high, and a hardness of Hv = 3000 or higher after diamond is obtained.

  Further, the surface of the slider 15 that faces the disk 2 has an air bearing surface (also referred to as an ABS (Air Bearing Surface) surface) for improving the flying characteristics. The flying of the slider 15 needs to be stabilized in the state of being close to the disk 2, and it is necessary to appropriately apply a pressure for suppressing the flying force to the slider 15. For this reason, the suspension 4 that supports the slider 15 has a function of appropriately applying a pressure that suppresses the flying force of the slider 15 in addition to the function of tracking the optical head 3.

  When the laser beam emitted from the optical head 3 is irradiated to the disk 2 as a minute spot, the temperature of the irradiated part of the disk 2 temporarily rises and the holding power of the disk 2 decreases. Magnetic information is written by the magnetic recording unit 17 to the irradiated portion in a state where the holding force is reduced.

  FIG. 3 is a cross-sectional view showing the configuration of the optical waveguide 12. As shown in FIG. 3A, the optical waveguide 12 includes a core waveguide 12a that propagates light and a clad 12b that covers the core waveguide 12a and blocks light leakage. The core waveguide 12a is bent into an L shape by approximately 90 degrees, and an inclined surface 12c inclined by approximately 45 degrees with respect to the optical axis K1 of the core waveguide 12a is formed at the bent portion.

  The laser light propagated from the direction of the arrow P is confined in the core waveguide 12a and maintains a constant waveguide mode (beam shape). In such a configuration, even after the laser light is deflected 90 degrees on the inclined surface 12c, the waveguide mode can be kept constant, so that the light use efficiency can be increased. Specifically, the size of this guided mode is set to about 3 μm to 10 μm by FWHM. On the other hand, as shown in FIG. 3B, in the configuration in which the inclined surface 12c is simply provided on the end face of the optical fiber, there is no structure for confining the laser light deflected by the inclined surface 12c, so the laser light propagates in free space. It will be. In this case, the laser beam deflected by the inclined surface 12c is spread by diffraction. The laser light emitted from the optical head 3 to the disk 2 needs to be focused as a fine spot as described above, but the optical waveguide 16 (light assist portion) provided in the slider 15 by the spread of the laser light by this diffraction. ) Decreases in the amount of light incident on the light source), leading to a decrease in light utilization efficiency.

  Next, the size of the optical waveguide 12 will be described with reference to FIG. First, when an optical fiber is used as the optical waveguide, for example, as shown in FIG. 4A, even if the optical fiber 13 having a core 13a diameter of 5 μm is used, the diameter of the clad 13b is usually 128 μm. The width of the clad 13b may be about the width of the core 13a in consideration of only light leakage, but the optical fiber 13 is set to such a size in consideration of strength, handling, and bending. ing. Although it is possible to reduce the diameter by using a technique such as etching, a great deal of labor is required, and it becomes very easy to break and is difficult to handle.

  On the other hand, FIG. 4B shows a basic shape of the optical waveguide 12 according to the present embodiment. As will be described later, the optical waveguide 12 is produced by laminating a plurality of materials on a substrate, and is cut to a desired width. It is possible to arbitrarily set the diameter of the clad 12b at the time of cutting (in this embodiment, for example, the width is set to 30 μm), and the production is easy. In FIG. 4B, the optical waveguide 12 is peeled off from the substrate, but may be configured not to peel off from the substrate as will be described later. Even when the optical waveguide 12 is peeled off from the substrate, it is excellent in flexibility and easy to handle if the optical waveguide 12 is made of a resin material such as polyimide. In this case, as will be described later, by providing a groove on the surface of the slider 15 and embedding the optical waveguide 12 in the groove, the entire thickness of the optical head 3 can be made extremely thin. Thus, in the optical waveguide 12 according to the present embodiment, the diameter of the clad 12b can be made larger and thinner than that of the optical fiber 13, so that the optical head 3 can be made thinner.

  Next, a method for manufacturing the optical waveguide 12 having such a configuration will be described with reference to FIG. 5A1 to 5A5 are process cross-sectional views of the optical waveguide 12 shown in FIG. 5B4 when viewed from the A-A ′ direction. 5 (b1) to 5 (b5) are process plan views.

  The optical waveguide 12 is manufactured on a wafer as shown in FIG. First, a clad layer 122 made of a resin material such as quartz or polyimide and a core layer 123 are sequentially laminated on a substrate 121 made of glass, silicon, ceramics or the like (FIG. 5 (a1)). For lamination, CVD, sputtering, spin coating, or the like is used. The core material is set to have a higher refractive index than the cladding material. Next, the core layer 123 is patterned into the shape of the core waveguide 12a by using a photolithography method or the like (FIG. 5 (a2)), and the over clad layer 124 is laminated thereon (FIG. 5 (a3)).

  In this way, the optical waveguide array 12A is completed on the wafer (FIG. 5 (b1)). Next, the optical waveguide array 12A formed on the wafer is separated by dicing (FIG. 5 (b2)), and an inclined surface 12c is formed by dicing polishing or the like (FIG. 5 (b3)). Next, the substrate 121 is peeled off to make only the optical waveguide 12D (FIG. 5 (a4)).

  Finally, for example, the optical waveguide 12 is obtained by dicing so as to have a width of 30 μm (FIG. 5A5, FIG. 5B4). Here, in order to emphasize that the width is reduced, the steps shown in FIGS. 5 (a5) and 5 (b4) are provided. Of course, this is changed from FIGS. 5 (b1) to 5 (b2). When shifting to the process shown, the width may be 30 μm. Further, as described later, a configuration with a substrate 121 is also conceivable.

  Next, a configuration example according to the first embodiment of the optical head 3 and an assembly process thereof will be described with reference to FIG. 6A to 6D are schematic views showing the configuration of the optical head 3 according to the first embodiment of the present invention and the assembly process of the optical head 3. FIG.

  First, as shown in FIG. 6A, four electrodes 15 </ b> D connected to an internal magnetic recording unit 17 and a magnetic reproducing unit 18 (not shown) are provided on the front surface of the slider 15. In addition, an optical waveguide 16 is provided at the front portion of the slider 15.

  Next, as shown in FIG. 6 (b), the light waveguide 12 is placed in the slider by aligning the light emitting position of the optical waveguide 12 with the light incident position of the optical waveguide 16 provided at the front of the slider 15. Adhere to 15.

  Next, the suspension 4 is bonded onto the slider 15 as shown in FIG. The suspension 4 is provided with a wiring member such as a lead wire (not shown) for propagating electrical signals between an external control circuit and the magnetic recording unit 17 and the magnetic reproducing unit 18 of the slider 15. Four electrodes 4D connected to the lead wires are provided on the front surface. Then, by connecting the electrode 15D provided on the slider 15 and the electrode 4D provided on the suspension 4 with solder, a control circuit (not shown) and the magnetic recording unit 17 and the magnetic reproducing unit 18 of the slider 15 are electrically connected. Connected to. Further, as shown in FIG. 6D, an optical fiber 11 is coupled to the optical waveguide 12, and an optical waveguide provided on the slider 15 with the light LD 1 guided through the optical fiber 11 from a light source (not shown). Lead to 16. FIG. 6D is a side sectional view of FIG.

As described above, in the optical head 3 according to the embodiment of the present invention, the optical waveguide 12 includes the core waveguide 12a that propagates light formed in an L shape, and the L-shaped bending of the core waveguide 12a. A slope 12c is provided at the portion, and the light propagated from the light source is reflected by the slope 12c and guided to the slider 15. That is, the light from the light source is reflected while being confined in the core waveguide 12 a and guided to the slider 15. Therefore, an optical system such as a lens for condensing light at a predetermined position of the slider 15 is not required, and the optical head 3 can be thinned. Moreover, the spread of light can be suppressed and the light utilization efficiency can be increased.
[Embodiment 2]
FIG. 7 shows a configuration example of the optical head 3 according to the second embodiment and an assembly process thereof. FIGS. 7A to 7D are schematic views showing the configuration of the optical head 3 according to the second embodiment of the present invention and the assembly process of the optical head 3. The configuration example according to the second embodiment and the assembly process thereof are substantially the same as those in the first embodiment, and only the form of the optical waveguide 12 is different.

As shown in FIG. 7B, the optical waveguide 12 according to the second embodiment has a configuration in which the substrate 121 is used without being peeled off. FIG. 7 is a conceptual diagram, and the scale and the like are different from actual ones. The actual size of the slider 15 is, for example, 1.25 mm (length) × 1.0 mm (width) × 0.3 mm (thickness), and the width of the optical waveguide 12 is 30 μm as described above, and the width of the substrate 121. (Thickness) is 350 μm. With this configuration, the manufacturing process of the optical waveguide 12 can be simplified, and the rigidity of the optical waveguide 12 can be increased.
[Embodiment 3]
FIG. 8 shows a configuration example of the optical head 3 according to the third embodiment and an assembly process thereof. FIG. 8A to FIG. 8C are schematic views showing the configuration of the optical head 3 according to Embodiment 3 of the present invention and the assembly process of the optical head 3.

  As shown in FIG. 8A, a groove 15m is formed in the slider 15 according to the third embodiment, and the optical waveguide 12 is embedded in the groove 15m.

  If the width of the groove 15m is made substantially the same as the width of the optical waveguide 12, it is possible to easily align the slider 15 with a predetermined position by moving the optical waveguide 12 along the groove 15m. Furthermore, as shown in FIG. 8A, if a wall 15k is provided at the end of the groove 15m so that the end can be aligned by contacting the end of the optical waveguide 12, the alignment can be further facilitated. When high accuracy is required for alignment, it may be difficult to achieve accuracy by simply abutting them. It is possible to combine them. Further, such a configuration is preferable because it is not necessary to avoid the optical waveguide 12 when fixing the suspension 4 as shown in FIG. 8B. Further, since the optical waveguide 12 is embedded in the groove 15m of the slider 15, the entire thickness of the optical head 3 can be extremely reduced.

1 is a perspective view showing a schematic configuration of an optically assisted magnetic recording apparatus according to Embodiment 1 of the present invention. It is sectional drawing which shows the structure of the optical head which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure of an optical waveguide. It is a schematic diagram explaining the size of an optical waveguide. It is a schematic diagram which shows the outline of the manufacturing process of an optical waveguide. FIG. 3 is a schematic diagram illustrating the configuration of an optical head according to Embodiment 1 and an outline of a manufacturing process. FIG. 6 is a schematic diagram illustrating a configuration of an optical head according to Embodiment 2 and an outline of a manufacturing process. FIG. 10 is a schematic diagram illustrating the configuration of an optical head according to Embodiment 3 and an outline of a manufacturing process.

Explanation of symbols

1A Optically Assisted Magnetic Recording Device 1 Housing 2 Disk 3 Optically Assisted Magnetic Recording Head (Optical Head)
4 Suspension 4D, 15D Electrode 5 Support shaft 6 Actuator 11 Optical fiber 12 Optical waveguide 12a Core waveguide 12b Cladding 12c Slope 121 Substrate 122 Cladding layer 123 Core layer 124 Over cladding layer 13 Optical fiber 13a Core 13b Cladding 15 Slider 15m Groove 16 Optical waveguide Light assist part)
17 Magnetic recording part 18 Magnetic reproducing part

Claims (5)

In an optically assisted magnetic recording head that records information using light on a recording medium,
A slider that moves relative to the recording medium;
An optical waveguide for guiding light from a light source to the slider,
The optical waveguide has a core waveguide that propagates light formed in an L shape,
An optically assisted magnetic recording head, wherein an inclined surface that reflects light propagated from the light source and guides it to the slider is formed at an L-shaped bent portion of the core waveguide. The core waveguide is bent at an angle of approximately 90 degrees and formed in an L shape,
The optically assisted magnetic recording head according to claim 1, wherein the inclined surface is formed at an angle of approximately 45 degrees with respect to the optical axis of the core waveguide. The slider is formed with a groove,
The optically assisted magnetic recording head according to claim 1, wherein the optical waveguide is embedded in the groove. A wall is formed at one end of the groove,
The optically assisted magnetic recording head according to claim 3, wherein one end of the optical waveguide is in contact with a wall formed in the groove. The optically assisted magnetic recording head according to any one of claims 1 to 4,
And a recording medium on which information is recorded by the optically assisted magnetic recording head.

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