WO2014024306A1

WO2014024306A1 - Near-field optical device and system

Info

Publication number: WO2014024306A1
Application number: PCT/JP2012/070510
Authority: WO
Inventors: 孝幸糟谷; 杉浦　聡
Original assignee: パイオニア株式会社
Priority date: 2012-08-10
Filing date: 2012-08-10
Publication date: 2014-02-13
Also published as: JPWO2014024306A1

Abstract

A near-field optical device is provided with a first member and a second member. A medium made of a material that is different from the first and second members is interposed between the first member and the second member. When the second member is a member that receives energy by means of near-field light generated in the first member, the second member is placed apart from the first member by a distance where the energy associated with the near-field light propagating through the medium is near a maximum. When the second member is a member that does not receive energy by means of near-field light, the second member is placed apart from the first member by a distance where the energy associated with the near-field light propagating through the medium is near a minimum.

Description

Near-field light device and system

The present invention relates to a technical field of a near-field light device that provides a minute spot in which energy is concentrated using, for example, near-field light, and a system in which the near-field light device is applied to, for example, a magnetic recording head.

As an example of using a nano-scale minute light spot that uses near-field light and exceeds the light diffraction limit, for example, heat-assisted magnetic recording, which is one of the methods for improving the recording density of magnetic recording media, has been proposed. (See Patent Documents 1 to 4).

JP 2009-163834 A JP 2010-146655 A JP 2010-146663 A JP 2003-045004 A

In the configuration of the recording head for heat-assisted magnetic recording described in Patent Documents 1 to 4, for example, the laser beam is condensed using an objective lens or an optical waveguide. It cannot be narrowed down to a size smaller than the wavelength of light. On the other hand, the metal conductor which is a near-field light generating part has a size of, for example, several tens of nanometers or less and a wavelength of light or less. For this reason, most of the condensed laser light does not contribute to the generation of near-field light, and there is a technical problem that the light use efficiency is low.

The present invention has been made in view of the above problems, for example, and an object thereof is to provide a near-field light device and system capable of efficiently generating near-field light.

In order to solve the above-described problem, the near-field light device of the present invention includes a first member and a second member. Between the first member and the second member, the first member and the second member When a medium made of a material different from the second member is interposed, and the second member is a member that receives energy via near-field light generated in the first member, the second member is: The first member is disposed away from the first member by a distance at which the energy related to the near-field light propagating in the medium becomes a local maximum, and the second member does not receive energy via the near-field light. In the case of a member, the second member is disposed away from the first member by a distance at which the energy of the near-field light propagating in the medium becomes a minimum.

The operation and other advantages of the present invention will be clarified from the embodiments to be described below.

It is a schematic block diagram which shows the structure of the near-field light device which concerns on embodiment. It is a conceptual diagram which shows the concept of the energy fluctuation | variation of the near field light which propagates in the medium. It is a schematic block diagram which shows the structure of the system using the near-field light device which concerns on 1st Example. It is a schematic block diagram which shows the structure of the system using the near-field light device which concerns on 2nd Example. It is a schematic block diagram which shows the structure of the system using the near-field light device which concerns on 3rd Example. It is a schematic block diagram which shows the structure of the system using the near-field light device which concerns on the modification of 3rd Example. It is a schematic block diagram which shows the structure of the system using the near-field light device which concerns on 4th Example. It is a schematic block diagram which shows the structure of the system using the near-field light device which concerns on the modification of 4th Example. It is a figure explaining an example of the magnetic recording using the magnetic head which concerns on an Example. It is a perspective view which shows schematic structure of the element which has an optical circuit. It is a figure which shows an example of a structure of the optical waveguide inside an optical circuit.

Embodiments according to the near-field light device of the present invention will be described with reference to FIG. 1 and FIG. FIG. 1 is a schematic configuration diagram illustrating a configuration of a near-field light device according to the embodiment. FIG. 2 is a conceptual diagram showing the concept of energy fluctuation of near-field light propagating in the medium. In each of the drawings referred to below, the scale of each layer and each member is different in order to make each layer and each member recognizable on the drawing.

In FIG. 1, the near-field light device according to this embodiment includes a part A and a part B. Between parts A and B, a medium made of a material different from parts A and B, such as air, a lubricant, and a dielectric, is interposed.

Here, when the near-field light propagates in the medium, it is known that the energy of the propagating near-field light attenuates while repeating small fluctuations as shown in FIG. University Computer andCompInformation Networking Center, Ding-wei Huang Prof .: http://homepage.ntu.edu.tw/~dwhuang/courses/spp/spp_7_1.pdf).

Using this phenomenon, if the distance L between part A and part B in FIG. 1 is set so that the intensity of the propagation energy becomes a mountain (that is, maximum) at the position of part B, part A to part A Energy can be propagated to B via near-field light. On the other hand, if the distance L is set so that the intensity of the propagation energy becomes a trough (that is, a minimum) at the position of the part B, the energy is not propagated from the part A to the part B.

Therefore, when the part B is a member that receives energy via the near-field light generated in the part A, if the distance L is set so that the intensity of the propagation energy becomes a mountain at the position of the part B, the part A Therefore, energy can be appropriately propagated to part B. In addition, when part B is a member that does not receive energy through near-field light generated in part A, if the distance L is set so that the intensity of propagation energy is a valley at the position of part B, the part It is possible to prevent unintended energy from being propagated from A to part B.

The “part A” and “part B” according to the present embodiment are examples of the “first member” and the “second member” according to the present invention, respectively.

<First embodiment>
A first embodiment of the system using the near-field light device of the present invention will be described with reference to FIG. FIG. 3 is a schematic configuration diagram illustrating a configuration of a system using the near-field light device according to the first embodiment.

In FIG. 3, a system 400 includes a near-field light device 200 and a recording medium 300. The near-field optical device 200 is laminated on the mesa-shaped semiconductor layer 15 made of, for example, Si (silicon), GaN (gallium nitride), GaAs (gallium arsenide), etc., and is made of, for example, SiO (silicon oxide). ), A dielectric layer 14 made of a dielectric such as VaO, and the like, laminated on the dielectric layer 14, for example, a metal film 13 made of Au (gold), etc., and laminated on the metal film 13, for example, A dielectric layer 12 made of a dielectric material such as SiO or VaO, and metal particles 11 laminated on the dielectric layer 12 and made of, for example, Au (gold), Ag (silver), or the like. Yes.

During operation, when light is incident on the near-field light device 200, energy resulting from the incident light is collected on the metal film 13. The energy collected on the metal film 13 propagates to the metal particles 11. The recording of information on the recording medium 300 uses, for example, that at least a part of the energy propagated to the metal particles 11 raises the temperature of a part of the recording medium 300 facing the metal particles 11 as near-field light. Done.

3, the distance between the metal particles 11 and the recording medium 300 is set to a distance A. A distance between the upper surface of the dielectric layer 12 and the recording medium 300 is set to a distance B. The distance between the upper surface and the lower surface of the dielectric layer 12 (that is, the thickness of the dielectric layer 12) is set to the distance C. The distance between the upper surface of the dielectric layer 14 and the recording medium 300 is set to the distance D.

Here, since it is desired to propagate energy from the metal particles 11 to the recording medium 300 via near-field light, the distance A is a near-field propagating in the air interposed between the metal particles 11 and the recording medium 300. The light energy intensity is set to be a mountain (see FIG. 2) at the position of the recording medium 300.

Further, since it is desired to propagate energy from the metal film 13 to the metal particles 11 via near-field light, the distance C is determined by the energy intensity of the near-field light propagating in the dielectric layer 12 at the position of the metal particles 11. Is set to be a mountain.

On the other hand, since it is not desired to propagate energy from the upper surface of the dielectric layer 12 to the recording medium 300, the distance B has a trough (see FIG. Reference) is set.

Similarly, since it is not desired to propagate energy from the upper surface of the dielectric layer 14 to the recording medium 300, the energy intensity of the near-field light propagating in the air becomes a valley at the position of the recording medium 300. Is set as follows.

The “distance A” and the “distance B” according to the present embodiment are the “first distance” according to the present invention, respectively.
And “second distance”.

<Second embodiment>
A second embodiment of the system using the near-field light device of the present invention will be described with reference to FIG. FIG. 4 is a schematic configuration diagram showing a configuration of a system using the near-field light device according to the second embodiment. In addition, about 2nd Example, while omitting the description which overlaps with 1st Example suitably, the same code | symbol is attached | subjected and shown to a common location on drawing.

4, the system 410 includes a near-field light device 210 and a recording medium 300. The near-field light device 210 includes a mesa-shaped semiconductor layer 15 made of, for example, Si, GaN, GaAs, and the like, and a dielectric layer 12 made of a dielectric such as SiO, VaO, etc., stacked on the semiconductor layer 15; The metal particles 11 are stacked on the dielectric layer 12 and made of, for example, Au, Ag, or the like.

During operation, when light is incident on the near-field light device 210, energy caused by the incident light propagates to the metal particles 11. The recording of information on the recording medium 300 uses, for example, that at least a part of the energy propagated to the metal particles 11 raises the temperature of a part of the recording medium 300 facing the metal particles 11 as near-field light. Done.

<Third embodiment>
A third embodiment of the system using the near-field light device of the present invention will be described with reference to FIG. FIG. 5 is a schematic configuration diagram showing a configuration of a system using the near-field light device according to the third embodiment. In addition, about 3rd Example, while overlapping with 1st Example is abbreviate | omitted suitably, the common code | symbol is attached | subjected and shown in drawing.

In FIG. 5, the system 420 includes a near-field light device 220 and a recording medium 300. The near-field light device 220 includes a mesa-shaped semiconductor layer 15 made of, for example, Si, GaN, GaAs, and the like, and a dielectric layer 12 made of a dielectric such as SiO, VaO, etc., stacked on the semiconductor layer 15; For example, a metal particle 11 made of Au, Ag, or the like is provided. Here, in particular, the metal particles 11 are covered with a dielectric layer 12. If comprised in this way, the metal particle 11 can be protected and it is very advantageous practically.

In addition, the metal particle 11 and the semiconductor layer 15 may be covered with the dielectric layer 12 like the near-field light device 230 of the system 430 shown in FIG. FIG. 6 is a schematic configuration diagram showing a configuration of a system using a near-field light device according to a modification of the third embodiment.

During operation, when light is incident on the near-field light device 220 or 230, energy caused by the incident light propagates to the metal particles 11. The recording of information on the recording medium 300 uses, for example, that at least a part of the energy propagated to the metal particles 11 raises the temperature of a part of the recording medium 300 facing the metal particles 11 as near-field light. Done.

<Fourth embodiment>
A fourth embodiment of the system using the near-field light device of the present invention will be described with reference to FIG. FIG. 7 is a schematic configuration diagram showing a configuration of a system using the near-field light device according to the fourth embodiment. In addition, about 4th Example, while overlapping with the 1st Example is abbreviate | omitted suitably, the common code | symbol is attached | subjected and shown in drawing.

7, the system 440 includes a near-field light device 240 and a recording medium 300. The near-field light device 240 is laminated on a semiconductor layer 16 having a mesa shape having a plurality of quantum dots made of, for example, InAs (indium arsenide), for example, inside a semiconductor made of, for example, GaAs, For example, a dielectric layer 12 made of a dielectric material such as SiO or VaO and metal particles 11 made of Au or Ag, for example, are provided. If comprised in this way, the energy of the light which injected into the semiconductor layer 16 can be propagated to the metal particle 11 comparatively efficiently by the quantum dot.

In addition, like the near-field light device 250 of the system 450 shown in FIG. 8, the semiconductor layer 17 includes a plurality of quantum dot layers in which quantum dots are regularly arranged in a lattice shape. May be. FIG. 8 is a schematic configuration diagram showing the configuration of a system using a near-field light device according to a modification of the fourth embodiment. Further, instead of quantum dots, for example, particles having a size that exhibits a quantum effect such as metal nanoparticles may be included in the semiconductor layer.

The band gap can be controlled freely by controlling the size of the quantum dots. Thereby, the semiconductor layer 16 can be designed so that light of an arbitrary wavelength can be efficiently absorbed and emitted. For example, white light from an LED (Light Emitting Diode) or the like is used as incident light, and the semiconductor layer 16 can absorb a wavelength suitable for the size of the quantum dots.

During operation, when light is incident on the near-field light device 240 or 250, energy caused by the incident light propagates to the metal particles 11. The recording of information on the recording medium 300 uses, for example, that at least a part of the energy propagated to the metal particles 11 raises the temperature of a part of the recording medium 300 facing the metal particles 11 as near-field light. Done.

<Application example>
Next, magnetic recording using the near-field light device according to the example for a magnetic head will be described with reference to FIG. FIG. 9 is a diagram illustrating an example of magnetic recording using the magnetic head according to the example. In FIG. 9, the near-field light device 230 shown in FIG. 6 is used. However, the present invention is not limited to the near-field light device 230, and various near-field light devices described above can be applied.

During operation, a light source such as a surface emitting laser is controlled so as to emit light according to an input signal. When energy caused by light incident on the near-field light device propagates to the metal particles 11, the metal particles 11 and a part of the magnetic recording medium 310 facing the metal particles 11 are integrated to generate magnetism. Energy is applied to the recording medium 310. As a result, the coercive force of the region of the magnetic recording medium 310 given energy by the near-field light is reduced, and magnetic recording by the writing magnetic pole can be easily performed. On the other hand, the recording signal recorded on the magnetic recording medium 310 is read by the reading magnetic pole. The recording density can be improved as the size of the metal particles 11 is reduced.

Here, in particular, the distance between the metal particles 11 of the near-field light device and the magnetic recording medium 310 is such that the energy intensity of the near-field light propagating in the air is a peak at the position of the magnetic recording medium 310 (see FIG. 2). Is set to a distance A that is For this reason, energy is efficiently transmitted to the portion of the magnetic recording medium 310 that faces the metal particles 11, so that the portion can be efficiently heated.

Also, the distance between the surface of the semiconductor layer facing the magnetic recording medium 310 in the near-field light device and the magnetic recording medium 310 is such that the energy intensity of the near-field light propagating in the air is such that the magnetic recording medium 310 Is set to a distance B which is a distance that becomes a valley (see FIG. 2). The “distance B” according to the application example is another example of the “second distance” according to the present invention.

The magnetic head is attached to the tip of an arm not shown here. The distance A and the distance B are realized by riding on the air flow generated by the rotation of the magnetic recording medium 310 and flying the magnetic head from the surface of the magnetic recording medium 310 at a certain height. Further, as a method of maintaining the distance A, a distance is measured by a photo sensor or the like (not shown), and a heater (not shown) provided at the tip of the arm is driven according to the measurement result to maintain the distance A. Also good. In addition, when using a system in which the tip of the arm moves in the lubricant instead of in the air, the distance between the peaks and valleys should be adjusted according to the energy intensity of the near-field light propagating in the lubricant. , Distance A and distance B are set.

Next, another application example in which the technical idea of the present invention is applied to an optical circuit will be described with reference to FIGS. FIG. 10 is a perspective view showing a schematic configuration of an element having an optical circuit. FIG. 11 is a diagram illustrating an example of a configuration of an optical waveguide inside the optical circuit.

In FIG. 11, five optical waveguides Line1, Line2, Line3, Line4, and Line5 are provided in the optical circuit. Fibers corresponding to input lines (see FIG. 10) are connected to the input-side end portions In1, In2, In3, In4, and In5 of the optical waveguides Line1, Line2, Line3, Line4, and Line5. On the other hand, output fibers corresponding to output lines (see FIG. 10) are connected to the output-side ends Out1, Out2, and Out3 of the optical waveguides Line1, Line2, and Line5. Here, in the optical circuit, near-field light is used for optical connection between optical waveguides.

Here, the distance between the optical waveguides to be optically connected is a distance at which the energy intensity of the near-field light propagating in the air becomes a mountain (see FIG. 2) in the optical waveguide to which the energy is to be propagated (see “Distance S see ₁ "and" distance _{S 2} "). On the other hand, the distance between the optical waveguides that are not desired to be optically connected is the distance at which the energy intensity of the near-field light propagating in the air becomes a valley in the adjacent optical waveguide (“distance W ₁ ”, “distance W ₂ ”). , “Distance W ₃ ”, “Distance W ₄ ”, “Distance W ₅ ” and “Distance W ₆ ”). As a result, the optical waveguide Line2 and the optical waveguide Line3, are optically connected to each other at a portion that is a distance _{S 1.} Similarly, the optical waveguide Line4 and the optical waveguide Line5, are optically connected to each other at a portion that is the distance _{S 2.}

In accordance with the inputs of the end portions In1, In2, In3, In4 and In5, an operation is performed in the optical circuit, and outputs are obtained from the end portions Out1, Out2 and Out3.

The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and the near-field light device with such a change And the system are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 11 ... Metal particle, 12, 14 ... Dielectric layer, 13 ... Metal film, 15, 16, 17 ... Semiconductor layer, 200, 210, 220, 230, 240, 250 ... Near field optical device, 300 ... Recording medium, 310 ... magnetic recording medium, 400, 410, 420, 430, 440, 450 ... system

Claims

A first member;
A second member;
With
A medium made of a material different from the first member and the second member is interposed between the first member and the second member,
When the second member is a member that receives energy via near-field light generated in the first member, the second member transmits the near-field light propagating in the medium from the first member. It is located at a distance where the energy concerned is close to the maximum,
When the second member is a member that does not receive energy via the near-field light, the second member is in the vicinity of a minimum energy related to the near-field light propagating in the medium from the first member. The near-field light device is characterized by being arranged at a distance of
A semiconductor layer made of a semiconductor;
A metal layer made of metal and laminated above the semiconductor layer;
A dielectric layer that is laminated immediately above the metal layer and is made of a dielectric;
An output end disposed immediately above the dielectric layer and capable of outputting at least part of the energy of near-field light generated in the metal layer to the outside;
With
The distance between the lower surface of the dielectric layer and the upper surface of the dielectric layer propagates on the upper surface of the dielectric layer when near-field light generated in the metal layer propagates through the dielectric layer. A near-field light device characterized in that the energy associated with near-field light is a distance near the maximum.
A system comprising a near-field light device and a recording medium disposed to face the near-field light device,
The near-field light device has an output end capable of outputting at least part of the energy of the near-field light generated in the near-field light device to the outside on the side facing the recording medium,
The distance between the output end and the recording surface, which is the surface facing the output end of the recording medium, is a near field generated at the output end in the medium interposed between the recording medium and the output end. When light propagates, the recording surface is a distance at which the energy associated with the propagating near-field light is near the maximum.
The near-field light device further includes a first dielectric layer that is laminated immediately below the output end and made of a dielectric,
The distance between the upper surface of the first dielectric layer and the recording surface is related to the near-field light propagating on the recording surface when the near-field light generated at the output end propagates in the medium. The system according to claim 3, wherein the distance is a distance at which energy becomes a minimum.
The near-field light device further includes a metal layer made of a metal, which is laminated immediately below the first dielectric layer, and a second dielectric layer made of a dielectric, which is laminated immediately below the metal layer. And
The distance between the lower surface of the first dielectric layer and the upper surface of the first dielectric layer is such that near-field light generated in the metal layer propagates through the first dielectric layer. A distance at which the energy associated with near-field light generated in the metal layer on the upper surface of the body layer is in the vicinity of the maximum,
The distance between the upper surface of the second dielectric layer and the recording surface is related to the near-field light propagating on the recording surface when the near-field light generated at the output end propagates in the medium. The system according to claim 4, wherein the energy is a distance at which the energy becomes a minimum.
The system according to claim 3, wherein the near-field light device further includes a quantum dot layer that is stacked below the output end and includes a plurality of quantum dots.
A semiconductor substrate; a dielectric layer formed on the semiconductor substrate; and metal particles formed on the dielectric layer, wherein energy of light incident on the semiconductor substrate is the dielectric layer and the A near-field light device that propagates through a metal particle to a recording medium disposed opposite to the metal particle and raises the temperature of a minute region on the recording medium,
The distance between the metal particle and the surface of the recording medium on the metal particle side is a first distance in which the amount of energy propagated is large.
The distance between the surface on the recording medium side of the dielectric layer and the surface on the metal particle side of the recording medium is a second distance with a small amount of the energy to propagate,
The near-field light device, wherein the first distance and the second distance are different from each other.
A recording medium comprising: a semiconductor layer; and metal particles formed above the semiconductor layer, wherein the energy of light incident on the semiconductor layer is disposed to face the metal particles through the metal particles A near-field light device that propagates to raise the temperature of a minute region on the recording medium,
The distance between the metal particle and the surface of the recording medium on the metal particle side is a first distance in which the amount of energy propagated is large.
The distance between the surface on the recording medium side of the semiconductor layer and the surface on the metal particle side of the recording medium is a second distance with a small amount of the energy to propagate,
The near-field light device, wherein the first distance and the second distance are different from each other.