JP2013038227A - Near-field optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance energy efficiency of a near-field optical device.SOLUTION: A near-field optical device comprises quantum dot layers (13, 14, 15) placed on a substrate (12) while containing a quantum dot (16), and capable of generating near-field light (18) by the light generation action of the quantum dot, by using the incident light introduced by the substrate as an energy source. The near-field optical device further includes an output end (17) placed on the quantum dot layer and capable of generating near-field light (65), by using the near-field light generated from the quantum dot layer as an energy source, and outputting the near-field light (65) to the outside.

Description

  The present invention relates to a near-field light device device using a minute spot of near-field light such as HAMR (Heat Assisted Magnetic Recording), SNOM (Scanning Near Field Optical Microscope), etc. About.

  Due to recent advances in semiconductor microfabrication technology, nanoscale quantum dots that utilize quantum mechanical effects and control the single particle electron to the utmost limit of electron particles are attracting attention. For example, a manufacturing method that appropriately controls the size of quantum dots (see Patent Document 1) and a near-field concentrator that uses stacked quantum dots have been proposed (see Patent Document 2).

JP 2009-231601 A JP 2006-080459 A

  In the near-field light device in the background art, there is a problem that it is difficult to improve the rate (energy efficiency) at which incident light is converted into near-field light.

  This invention is made | formed in view of the said subject, for example, and makes it a subject to provide the near-field optical device which can improve energy efficiency, and its manufacturing method.

<1>
In order to solve the above problems, a first near-field light device of the present invention is arranged on a substrate and the substrate, includes a first quantum dot, and uses incident light guided by the substrate as an energy source. A quantum dot layer capable of generating a first near-field light by a light generating action of the first quantum dot; and the quantum dot layer disposed on the quantum dot layer, including the second quantum dot, and generated in the quantum dot layer An output terminal capable of generating second near-field light by the light generation action of the second quantum dots using the first near-field light as an energy source and outputting the second near-field light to the outside.

  According to the first near-field light device, in operation, incident light is guided to the quantum dot layer by the substrate. Here, regarding the “substrate”, incident light may be guided (for example, in the vertical direction of the substrate) by a substrate body which is a transparent substrate, for example. Alternatively, the angle may be changed after incident light is guided (for example, in a direction along the substrate) by an optical member such as a light guide, a waveguide, or a grating provided on the substrate.

  In the quantum dot layer, the incident light is used as an energy source, and first near-field light is generated by the light generation action of the first quantum dots. Here, the “light generation action” of the first quantum dots means the near-field light generation action (in other words, “quantum mechanical effect or action”).

  Further, at the output end, the near-field light is used as an energy source, and second near-field light is generated by the light generating action of the second quantum dots and is output to the outside. Here, the “light generation effect” of the second quantum dot means the near-field light generation effect. Further, “external” typically refers to the surface of a recording medium arranged in proximity, the input end of an output waveguide, or the like. Near-field light is output from the output end to the outside.

According to the research of the present inventor, when the output end including the “second quantum dot” is used as in the first near-field light device, the first end is compared with the case where the output end including a simple metal end is used. It has been found that the energy efficiency until the near-field light generated in the quantum dot is output to the outside through the output end is remarkably improved. That is, according to the present invention, the energy efficiency in the near-field light device can be significantly increased by the action of the “second quantum dot” or the like.
<2>
In order to solve the above problems, a second near-field light device of the present invention includes a substrate and the quantum dot that is disposed on the substrate, includes quantum dots, and uses incident light guided by the substrate as an energy source. A quantum dot layer capable of generating near-field light by the light generation action, and an output end that is disposed on the quantum dot layer and capable of outputting the near-field light generated in the quantum dot layer to the outside, An energy concentrating layer that is disposed between the substrate and the quantum dot layer and concentrates the energy of the guided incident light toward at least one of the quantum dot layer and the output end;

  According to the second near-field light device, in operation, incident light is guided to the quantum dot layer by the substrate. Here, regarding the “substrate”, incident light may be guided (for example, in the vertical direction of the substrate) by a substrate body which is a transparent substrate, for example. Alternatively, the angle may be changed after incident light is guided (for example, in a direction along the substrate) by an optical member such as a light guide, a waveguide, or a grating provided on the substrate.

  In the quantum dot layer, this incident light is used as an energy source, and near-field light is generated by the light generation action of the quantum dots. Here, the “light generation effect” of the quantum dots means the near-field light generation effect.

  Here, in particular, the energy concentration layer disposed between the substrate and the quantum dot layer concentrates the energy of incident light guided by the substrate toward at least one of the quantum dot layer and the output end.

  Further, the near-field light is output to the outside at the output end. Here, “external” typically refers to the surface of a recording medium arranged in proximity, the input end of an output waveguide, or the like. Further, the “output end” may be a metal end, or a non-metal end including other quantum dots, for example.

  Therefore, compared with the case where there is no energy concentration layer, the incident light component or the energy component related to the incident light, which will pass or diverge without being concentrated toward the quantum dot layer or the output end, Remarkably reduced. Here, the “energy concentration layer” is composed of, for example, an antenna layer having a predetermined pattern or a predetermined plane pattern in which a metal part and a non-metal part concentrate energy to an output end in a plane. As such a pattern, various known or existing patterns used for concentrating electromagnetic waves in the technical field of antennas at a desired location can be adopted.

As described above, according to the present invention, the energy efficiency in the near-field light device can be remarkably increased by the action of the “energy concentration layer” or the like.
<3>
In order to solve the above problems, the third near-field light device of the present invention is disposed on the substrate and the substrate, and can generate near-field light using incident light guided by the substrate as an energy source. And a near-field light generating part capable of outputting the generated near-field light to the outside from an output end facing away from the substrate, and the near-field light generating part is provided in the protective layer and the protective layer. The protective layer includes a plurality of metal nanoparticles that are discretely arranged and each function as a quantum dot, and the width of the protective layer becomes narrower from the substrate side toward the output end side in the external shape. A taper is provided.

  According to the third near-field light device, incident light is guided to the near-field light generating unit by the substrate during the operation. Here, regarding the “substrate”, incident light may be guided (for example, in the vertical direction of the substrate) by a substrate body which is a transparent substrate, for example. Alternatively, the angle may be changed after incident light is guided (for example, in a direction along the substrate) by an optical member such as a light guide, a waveguide, or a grating provided on the substrate.

  Here, in particular, the near-field light generating part is formed by discretely arranging a plurality of metal nanoparticles each functioning as a quantum dot in a protective layer including, for example, silicate glass. In the metal nanoparticles, incident light is used as an energy source, and near-field light is generated by the action of generating near-field light as quantum dots.

  For example, 130,000 metal nanoparticles (20 nm fine particle 20 nm interval) to 1.6 million (5 nm fine particle 5 nm interval) per unit volume (1 cubic μm) may be three-dimensionally dispersed in the protective layer. In this way, efficient near-field light can be propagated.

  Further, the protective layer in which the metal nanoparticles are discretely arranged in the inside has an external shape so that the width becomes narrower from the substrate side toward the output end side, that is, toward the outside. A taper is provided so as to be sharp. That is, the external shape of the protective layer is typically a truncated cone shape, a truncated pyramid shape, a bank shape, or the like.

  Then, near-field light generated from the plurality of metal nanoparticles is output to the outside at the output end facing the side opposite to the substrate. Here, “external” typically refers to the surface of a recording medium arranged in proximity, the input end of an output waveguide, or the like. Further, the “output end” may be a metal end, or a non-metal end including other quantum dots, for example. Further, the “output end” may be configured by attaching a metal end, a quantum dot, or the like separately from the protective layer to the narrow tip portion of the near-field light generating portion. Or the narrow front-end | tip part in a protective layer may function as an output end as it is. In either case, near-field light is output from the tip end of the output end that is sharper than the root toward the outside on the opposite side of the substrate from the back.

According to the research of the present inventor, as in the second near-field light device, a “near-field light generating portion including“ metal nanoparticles discretely arranged in the protective layer ”and having a“ taper ”is used. Compared with the case of using a shape without a simple quantum dot or taper, the energy efficiency until the near-field light generated by the near-field light generating unit is output to the outside through the output end is remarkably improved. Has been found to be. That is, according to the present invention, the energy efficiency in the near-field light device can be remarkably increased by the actions such as “metal nanoparticles discretely arranged in the protective layer” and “taper”.
<4>
In order to solve the above problems, a fourth near-field light device of the present invention is arranged on a substrate and the substrate, and can generate near-field light using incident light guided by the substrate as an energy source. And the near-field light generating part capable of outputting the generated near-field light to the outside from the output end facing the opposite side of the substrate, and disposed between the substrate and the near-field light generating part, The guided incident light is transmitted from the substrate side toward the near-field light generation unit side, and the near-field light generated by the near-field light generation unit is directed toward the near-field light generation unit side. A reflective layer for reflecting.

  According to the fourth near-field light device, incident light is guided to the near-field light generating unit by the substrate during the operation. Here, regarding the “substrate”, incident light may be guided (for example, in the vertical direction of the substrate) by a substrate body which is a transparent substrate, for example. Alternatively, the angle may be changed after incident light is guided (for example, in a direction along the substrate) by an optical member such as a light guide, a waveguide, or a grating provided on the substrate.

  Then, the near-field light generated by the near-field light generating unit is output to the outside at the output end facing the side opposite to the substrate. Here, the “near-field light generating portion” is typically a portion that includes quantum dots and generates near-field light by a near-field light generating action. “External” typically refers to the surface of a recording medium that is closely arranged, the input end of an output waveguide, or the like. Further, the “output end” may be a metal end, or a non-metal end including other quantum dots, for example.

  Here, in particular, a reflective layer is disposed between the substrate and the near-field light generator. Here, the “reflective layer” is a reflective layer or a semi-transmissive reflective layer that has frequency dependency or wavelength dependency and selectively reflects or transmits, such as a dielectric mirror. Regarding the wavelength or frequency of incident light, the transmittance of the reflective layer when transmitting from the substrate side toward the near-field light generating unit side is the opposite, when transmitting from the near-field light generating unit side toward the substrate side. For example, a value of 50% or more. Furthermore, with respect to the wavelength or frequency of the near-field light, the reflectance of the reflective layer when reflecting the near-field light toward the near-field light generation unit side is the reflectance when reflecting the incident light toward the substrate side or The value is higher than when the near-field light is virtually reflected toward the substrate side, for example, 50% or more.

  Therefore, the incident light guided by the substrate is transmitted from the substrate side toward the near-field light generating unit side by the reflective layer disposed between the substrate and the near-field light generating unit. That is, the near-field light generating unit can obtain energy necessary for generating near-field light from incident light incident through the reflective layer. On the other hand, the component that is generated by the near-field light generating unit (not the component that directly proceeds to the output end side) but returns to the substrate side is a reflection layer disposed between the substrate and the near-field light generating unit. Is reflected toward the near-field light generator. In other words, the component that returns to the substrate side can be changed to a component that tends to advance toward the output end side by the reflection action in the reflection layer.

  Therefore, compared with the case where there is no reflective layer, the near-field light component that returns to the substrate side or diverges from the output end (without being output to the outside) is significantly reduced. I'll be caught. As described above, according to the present invention, the energy efficiency of the near-field light device can be remarkably increased by the action of the “reflection layer” or the like.

  The effect | action and other gain of this invention are clarified from the form for implementing demonstrated below.

1 is a schematic cross-sectional view showing a schematic structure of a near-field light device according to a first embodiment. It is a figure of the same meaning as FIG. 1 which shows the modification of the near-field light device which concerns on 1st Embodiment. It is a perspective view (Drawing 3 (a)) and a sectional view (Drawing 3 (b)) showing a schematic structure of a near-field light device concerning a 2nd embodiment. FIG. 5 is a schematic plan view (FIGS. 4A to 4F) showing various patterns of an antenna layer according to a second embodiment. FIG. 6 is a schematic cross-sectional view showing a schematic structure of a near-field light device according to a third embodiment. It is process drawing which shows the manufacturing process of the near-field optical device which concerns on 3rd Embodiment. It is a figure of the same meaning as FIG. 5 which shows the modification of the near-field light device which concerns on 3rd Embodiment. It is a perspective view (Drawing 8 (a)) and a sectional view (Drawing 8 (b)) showing a schematic structure of a near field light device concerning a 4th embodiment.

  Hereinafter, embodiments of the near-field light device of the present invention will be described with reference to the drawings. In the following drawings, the scales are different for each layer and each member so that each layer and each member can be recognized on the drawing.

<First Embodiment>
1st Embodiment which concerns on the near-field optical device of this invention is described with reference to FIG.1 and FIG.2. First, the near-field light device of FIG. 1 using quantum dots to which the present invention is applied will be described. The near-field light device has a near-field light generating unit 1, and as shown in FIG. 1, a light source 11, a GaAs substrate 12, a GaAs buffer layer 13, an InAs layer 14, a GaAs layer 15, an InAs quantum dot 16, and a metal It consists of an end 17.

  The present embodiment is an embodiment of the first near-field optical device according to the present invention, wherein “GaAs substrate 12” constitutes an example of “substrate” according to the present invention, and “InAs quantum dots 16” are present in the present invention. An example of the “first quantum dot” according to the present invention is configured, and “GaAs buffer layer 13, InAs layer 14, GaAs layer 15 and InAs quantum dot 16” constitute an example of the “quantum dot layer” according to the present invention. .

  Although the light source 11 and the GaAs substrate 12 are joined in FIG. 1, they may be separated. The light source 11 may be an LED (Light Emitting Diode), a semiconductor laser, or a surface emitting laser. The GaAs substrate 12 is designed to have a thickness through which incident light from the light source 11 is transmitted. The metal edge 17 is preferably a metal (for example, gold (Au)) having an energy band that can efficiently absorb the energy of near-field light, but is not limited thereto and may be a metal other than gold (Au). Various semiconductors may be used. The quantum dot structure shown in FIG. 1 is manufactured by, for example, a method described in JP2009-231601A.

  In the example of the near-field light device in FIG. 1, GaAs or InAs is used. However, the material is not limited to these materials, and a material that functions as a light-transmitting quantum dot such as CuCl, GaN, or ZnO can be used. .

  Next, a method in which the near-field light device 1 in FIG. 1 moves the energy of incident light from the light source 11 will be described. Incident light from the light source 11 passes through the GaAs substrate 12, the GaAs buffer layer 13, and the InAs layer 14, reaches the InAs quantum dots 15, and near-field light 18 is generated around the InAs quantum dots 15. The energy of the generated near-field light 18 moves to the metal end 17 and becomes the near-field light 65. The near-field light 65 moved to the metal edge 17 has a metal edge 17 when the distance between the target recording medium 601 and the metal edge 17 is a distance that causes a near-field interaction (for example, 20 nm (nanometer) or less). To the metal regions 603a, 603b, 603c,... (That is, the metal region 603a in the state of FIG. 1) on the surface of the recording medium 601 (ie, the energy moves). The metal regions 603a, 603b, 603c,... Constituting the minute spot are nano-order spots smaller than the diffraction limit of light.

  If the recording medium 601 is a magnetic recording medium, the metal regions 603a, 603b, 603c,... Constituting the minute spot are irradiated with energy such as heat, so that the temperature rising region can be reduced. A magnetic recording bid having a small area (volume) can be formed.

  By controlling ON / OFF of the light source 11 by the control unit 70, energy transfer from the metal end 17 to the metal regions 603a, 603b, 603c,... Is controlled. Thereby, for example, magnetic recording bits are recorded.

  The recording medium 601 includes a non-metal region 602 and metal regions 603a to 603c dispersed in an island shape. The non-metallic region 602 is made of resin, glass, or the like, and is made of a material that does not generate near-field light integrally with the metal end 17 of the near-field light generating unit 1. The metal regions 603a, 603b, 603c,... Are magnetic bodies including a metal such as gold (Au) that is integrated with the metal end 17 of the near-field light generating unit 1 and generates near-field light. Each metal region 603a, 603b, 603c,... Is isolated by a non-metal region 602. Further, the non-metallic region 602 is not limited to a non-metal, and may be formed of a non-magnetic material that does not generate near-field light integrally with the metal end 17 of the near-field light generating unit 1.

  When information is recorded on the recording medium 601 by the near-field light device configured in this way, the distance between the metal end 17 at the tip of the near-field light generating unit 1 and the recording medium 601 is a predetermined distance or less (for example, 20 nm or less). The light source 11 is turned on by the control unit 70. The near-field light 18 is generated in the InAs quantum dots 16 by the incident light, and the energy of the near-field light 18 moves to the metal edge 17. Then, near-field light 65 is generated so as to surround the metal edge 17 and the metal region 603 a of the recording medium 601. The metal end 17 and the metal region 603a are integrated to generate near-field light 65. Due to the energy of the near-field light 65, the metal region 603a itself (the metal region 603a and its surroundings) generates heat. As a result, the holding force of the metal region 603a is lowered, and magnetic recording can be performed in accordance with a magnetic field derived from a recording head (not shown).

  FIG. 2 shows a modification of the first embodiment shown in FIG. 1. In FIG. 1, the output end 17 is made of metal, but in FIG. 2, the output end is a quantum dot 17d. The quantum dot 17d is manufactured in the same manner as the InAs quantum dot 16. That is, the quantum dot 17d is configured as, for example, an InAs quantum dot.

  This modification is another embodiment of the first near-field light device according to the present invention, and the “quantum dot 17d” constitutes an example of the “second quantum dot” according to the present invention.

  According to this modification, when information is recorded on the recording medium 601 by the near-field light device configured as described above, the quantum dots 17d constituting the output end of the “first near-field light” according to the present invention are used. The near-field light 18 as an example is used as an energy source, and the near-field light 65 as an example of the “second near-field light” according to the present invention is generated by the light generation action (that is, “quantum mechanical effect”). The Further, the near-field light 65 is output to the recording medium 601 which is an example of “external” according to the present invention.

  According to the research of the present inventor, when the output end including the quantum dot 17d is used as in the modification of FIG. 2, the output end including only the metal end 17 is used as in the embodiment of FIG. It has been found that the energy efficiency until the near-field light 18 generated by the InAs quantum dots 16 is output to the recording medium 601 as the near-field light 65 via the output end is remarkably improved. That is, according to this modification, the energy efficiency in the near-field light device can be remarkably enhanced by the action of the quantum dots 17 and is significantly advantageous from the viewpoint of energy efficiency as compared with the embodiment of FIG. .

  On the other hand, in the case of the embodiment of FIG. 1, since the output end only needs to be configured from the metal end 17, the manufacturing thereof can be made relatively easy as compared with the modification of FIG.

  As described above in detail, according to the first embodiment or the modification thereof, it is possible to dramatically improve the energy efficiency mainly by the action of the metal end 17 or the quantum dot 17d.

Second Embodiment
A second embodiment of the near-field light device of the present invention will be described with reference to FIGS. The second embodiment is the same as the first embodiment except that the configuration of the near-field light device is partially different. Therefore, in the second embodiment, the description overlapping with that of the first embodiment is omitted, and the common portions on the drawing are denoted by the same reference numerals, and only the points that are basically different are described with reference to FIG. explain.

  3A is a perspective view of the near-field light device according to the present embodiment, and FIG. 3B is a cross-sectional view taken along the line AA ′ in FIG.

  In FIG. 3, the near-field light device 100 includes a light source 20, a transparent substrate 21 stacked on the light source 20, a near-field light generating unit 1 stacked on the transparent substrate 21, and the near-field. The antenna layer 22 is configured to surround the light generation unit 1 and cover the upper surface of the transparent substrate 21.

  This embodiment is an embodiment of the second near-field light device according to the present invention, and the antenna layer 22 constitutes an example of the “energy concentration layer” according to the present invention.

  As the light source 20, for example, an LED (Light Emitting Diode), a semiconductor laser, a VCSEL (Vertical Cavity Surface Emitting Laser), an organic EL, or the like is applicable. The transparent substrate 21 may be any substrate that can transmit at least the light that can appropriately operate the near-field light generating unit 1 out of the light emitted from the light source 20. For example, the transparent substrate 21 has a high light transmittance such as a glass substrate. It is not restricted to the board | substrate which has.

  The near-field generating unit 1 in FIG. 3 is expressed as including the GaAs substrate 12 to the metal end 17 of the near-field device 1 described in FIG. Note that the output end may be composed of quantum dots 17d (not the metal end 17) as in the modification of FIG.

  Here, according to the inventor's research, the following matters have been found. That is, even if the light emitted from the light source 20 is condensed by a lens or the like, the diameter of the spot formed on the upper surface of the transparent substrate 21 (that is, the boundary surface between the transparent substrate 21 and the antenna layer 22) It is several hundred nm to several μm (μm). On the other hand, the size of the near-field light generating unit 1 (that is, the length of one piece in a plan view) is several tens nm to several hundreds nm. Then, light that is not incident on the near-field light generator 1 out of the light emitted from the light source 20 may leak from the vicinity of the near-field light generator 1. However, in this embodiment, the antenna layer 22 is provided on the upper surface of the transparent substrate 21, and the energy of the incident light can be absorbed by the antenna and concentrated on the near-field generating portion.

4 (a) to 4 (f) show variations of the antenna layer 22. In each of these drawings, the antenna layer 22 is configured such that the metal portion 22a and the non-metal portion 22b form a predetermined plane pattern. . The metal portion 22a is made of a metal such as Au, Ag, or Al, for example. The non-metallic portion 22b is made of a semiconductor such as gallium arsenide silicon, for example. The thickness of the metal portion 22a is, for example, 50 nm, and the thickness of the non-metal portion 22b is, for example, 50 nm. Accordingly, the antenna layer 22 including two kinds of material portions is configured as a layer having a flat and uniform thickness of, for example, a thickness of 50 nm.

  In each of these drawings, the size of the near-field light generating unit 1 (that is, the length of one piece in a plan view) is, for example, several tens nm to several hundreds nm, and the size of the metal end 17 (that is, The length of a piece in a plan view is, for example, several nm to several tens of nm smaller than the near-field light generating unit 1. On the other hand, the size of the antenna layer 22 (that is, the length of one piece in plan view) is, for example, on the order of several μm, and is much larger than the near-field light generating unit 1 and the metal end 17. .

  Specifically, FIG. 4A shows that approximately two diagonal lines are border lines, and about half (two regions occupying the upper and lower sides in the figure) are alternately formed as metal parts 22a and the remaining part as non-metal parts 22b. Pattern. FIG. 4B is a pattern in which approximately two diagonal lines are used as boundary lines, and about half (two regions occupying the left and right in the figure) are alternately metal portions 22a and the remaining portions are non-metal portions 22b. FIG. 4C shows a pattern in which a circle surrounding the near-field light generating unit 1 is a non-metal portion 22b and the remaining portion is a metal portion 22a. FIG. 4D shows a pattern in which metal portions 22a and non-metal portions 22b are laid out alternately and concentrically. FIG. 4D shows a pattern in which the metal portion 22a is arranged in a ring shape and the remaining portion is a non-metal portion 22b. FIG. 4 (f) shows a pattern in which the non-metallic portion 22b is laid out in a star shape that extends obliquely vertically and horizontally, and the remaining portion is the metallic portion 22a.

  According to the research of the present inventor, each of the patterns shown in these figures is an existing pattern for concentrating radio wave energy closer to the center with a radio wave receiving antenna. The energy of the incident light for generating the light 18 is closer to the center of the near-field light generating unit 1 when viewed in plan on the antenna layer 22 (that is, the metal end 17 as the center position in plan view). It can also be applied as a pattern that concentrates toward (position). Theoretically, light that is a type of electromagnetic wave (incident light in this case) is converted into an electromagnetic wave component along the plane of the antenna layer 22 toward the near-field light generating unit 1 that is nano-order, and closer to the center. Concentrated.

  Moreover, although the example which provided the antenna layer 22 between the transparent substrate 21 and the near field generation | occurrence | production part 1 was shown in the example of FIG. 4, it is not restricted to this, The inside of the transparent substrate 21 or the near field generation | occurrence | production part 1 is shown. You may make it form in the part of the GaAs substrate 12-quantum dot layer (the part under the output end 17).

  As described above in detail, according to the second embodiment, the energy efficiency can be dramatically improved mainly by the action of the antenna layer 22.

<Third Embodiment>
A third embodiment of the near-field light device of the present invention will be described with reference to FIG.

  FIG. 5 is a diagram showing a schematic structure of the near-field light device according to the present embodiment having the same concept as in FIG. In FIG. 5, the near-field light device 300 has a glass substrate 30 that is a transparent substrate, and a forward tapered shape in which a plurality of metal nanoparticles 31 are formed in the protective layer 32 and are formed on the glass substrate 30. A tapered portion 34 is provided.

  This embodiment is an embodiment of a third near-field light device according to the present invention, and the tapered portion 34 constitutes an example of a “near-field light generating portion” according to the present invention.

  As shown in FIG. 5, the vicinity of the tapered portion 34 is formed by discretely arranging a large number of metal nanoparticles 31 each functioning as a quantum dot in a protective layer 32 including, for example, silicate glass. In the metal nanoparticles 31, incident light is used as an energy source, and near-field light 18 is generated at the tip of the tapered portion 34 by a quantum mechanical effect.

  For example, 130,000 (20 nm fine particle 20 nm interval) to 1.6 million (5 nm fine particle 5 nm interval) metal nanoparticles may be three-dimensionally dispersed in the protective layer 32 per unit volume (1 cubic μm). . In this way, efficient near-field light propagation is possible. Alternatively, a configuration in which 200 to 800 metal nanoparticles per unit area (specifically, around 1 μm square) are two-dimensionally dispersed is stacked in the direction of the direction of the two-dimensional surface. May be.

  For example, the metal nanoparticles 31 can be formed of particles having a diameter of about 10 to 50 nm, and a gap of the same order exists between the metal nanoparticles 31. The height of the tapered portion 34 is, for example, about several tens to several hundreds nm, and is sufficiently larger than the diameter of the metal nanoparticles 31. The width at the base of the taper portion 34 is, for example, 100 nm, and the width at the tip formed narrow by forward taper is, for example, about 20 to 30 nm. The overall shape of the tapered portion 34 is a shape such as a truncated cone, a truncated pyramid (typically a rectangular truncated pyramid), or a bank shape extending longitudinally in any direction when viewed three-dimensionally.

  An output end such as a metal end 17 (see FIG. 1) or a quantum dot 17b (see FIG. 2) may be separately provided at the tip (upper end in FIG. 5) of the tapered portion 34. Alternatively, for example, if the tip of the tapered portion 34 is configured to protrude sufficiently narrowly (specifically, enough to transmit the near-field light 18 to the recording medium side), the protrusion at such a tip. The portion or the protrusion may be used as the output end as it is. With this configuration, the near-field light 18 can be directly output to the recording medium 601 (see FIGS. 1 and 2). In any case, from the front end side of the tapered portion 34 that is sharper than the root, approaching to the outside on the opposite side (upper side in FIG. 5) from the glass substrate 30 to the outside. The field light 18 is output.

  According to the research of the present inventor, when configured as described above, the quantum mechanical effect of the metal nanoparticles 31 in the tapered portion 34 interacts with each other, thereby dispersing the energy of incident light over the entire tapered portion 34. It is possible to concentrate the tip of the taper 34 very efficiently through the metal nanoparticles 31. As a result, the near-field light 18 can be generated from the incident light with high energy efficiency. In particular, as shown in FIG. 5, the proximity generated by the taper portion 34 is compared to the case where no forward taper is provided or the case where only the quantum dots 16 (see FIG. 1) are used instead of the metal nanoparticles 31. It has been found that the energy efficiency until the field light is output to the outside is significantly improved.

  Here, with reference to FIG. 6, the manufacturing method of 3rd Embodiment comprised as mentioned above is demonstrated. FIG. 6 is a process diagram illustrating the planar process for forming the near-field light device 300 of FIG. 5 on the glass substrate in order from process S1 to S6.

  As shown in FIG. 6, first, in step S1, a glass substrate 301 from which the glass substrate 30 is to be cut out is prepared. The glass substrate 301 has a large size including a large number of glass substrates 30, and a large number of near-field light devices 300 as shown in FIG. 5 are formed simultaneously by the steps S2 to S6 described below.

  Subsequently, in step S <b> 2, a silicate glass 302 that is a precursor of the protective film 32 (that is in a liquid state) in which the metal nanoparticles 31 are dispersed almost uniformly at a predetermined concentration is spin-coated on the glass substrate 301. Is done. Here, the spin coating is performed so that the film thickness is, for example, several tens to several hundreds of nm, which is approximately the same as the height of the tapered portion 34.

  Subsequently, in step S <b> 3, the silicate glass 302 is annealed at a predetermined baking temperature to form a silicon oxide film 303. In other words, a silicon oxide film 303 is formed in which the thickness is about several tens to several hundreds of nm, which is substantially the same as the height of the tapered portion 34, and the metal nanoparticles 31 are discretely arranged in a substantially uniform manner at a predetermined concentration.

  Subsequently, in step S4, a resist 304 for subjecting the silicon oxide film 303 to photolithography and etching is coated. It is also possible to use lift-off with a metal mask.

  Subsequently, in step S5, the resist 304 is subjected to a baking process by performing dry etching or wet etching, or by performing ion trimming, leaving the resist 305 in a minute region where the tapered portion 34 is to be formed.

  Subsequently, in step S6, the silicon oxide film 303 is subjected to dry etching, wet etching, or the like through the resist 305 that is baked and hardened after patterning, so that the tapered portion 34 is formed. At this time, it is also possible to adjust the degree of forward taper in the tapered portion 34 (that is, how much it is inclined) by managing the etching time. By using photolithography and etching in this manner, a tapered portion 34 that is a mesa structure and has a forward taper is formed in a region corresponding to the resist 305.

  Thereafter, the glass substrate 301 is subjected to a cutting process or the like, and a near-field light in which a tapered portion 34 in which a large number of metal nanoparticles 31 are discretely arranged is formed on the glass substrate 30 as shown in FIG. Device 300 is completed.

  Next, a modification will be described with reference to FIG.

  In the case of the near-field light device 350 according to the modification in FIG. 7, incident light is incident along the plane of the glass substrate 30 through the waveguide 354 provided on the upper surface of the glass substrate 30. Furthermore, the incident light guided by the waveguide 354 is bent toward the tapered portion 34 (upper side in FIG. 7) by grating, and as viewed from the tapered portion 34, the incident light is directed upward in the same vertical direction as in FIG. Incident light (from the bottom to the top in the figure) is incident. Other configurations and operations are the same as those of the third embodiment shown in FIG. A scattering plate can be used instead of the grating.

  Thus, in the case of the modified example, the degree of freedom of the optical path of incident light is increased, and the type of light source, the degree of freedom of optical design, and the like are remarkably increased.

  As described above in detail, according to the third embodiment and the modification thereof, the energy efficiency is remarkably improved by adopting the tapered portion 34 mainly composed of the protective layer 32 in which the metal nanoparticles 31 are dispersed. It becomes possible to make it.

<Fourth embodiment>
A fourth embodiment of the near-field light device of the present invention will be described with reference to FIG.

  FIG. 8A is a perspective view of the near-field light device according to the present embodiment, and FIG. 8B is a cross-sectional view taken along the line AA ′ of FIG.

  In FIG. 8, the near-field light device 400 includes a light source 40, a transparent substrate 41 stacked on the light source 40, a near-field light generator 1 stacked on the transparent substrate 41, and a transparent substrate 41. A reflection layer 42 that surrounds the vicinity of the near-field light generating unit 1 in plan view and covers the entire upper surface of the transparent substrate 41 is provided.

  This embodiment is an embodiment of the fourth near-field light device according to the present invention, and the reflective layer 42 selectively transmits incident light from the substrate side according to the present invention and the near-field light generator side. This constitutes an example of a “reflective layer” that selectively reflects light from the light source.

  As the light source 20, for example, an LED (Light Emitting Diode), a semiconductor laser, a VCSEL (Vertical Cavity Surface Emitting Laser), an organic EL, or the like is applicable. The transparent substrate 21 may be any substrate that can transmit at least the light that can appropriately operate the near-field light generating unit 1 out of the light emitted from the light source 20. For example, the transparent substrate 21 has a high light transmittance such as a glass substrate. It is not restricted to the board | substrate which has.

  The near-field generating unit 1 in FIG. 8 is expressed as including from the GaAs substrate 12 to the metal end 17 of the near-field device 1 described in FIG. Note that the output end may be composed of quantum dots 17d (not the metal end 17) as in the modification of FIG.

  The reflection layer 42 has a frequency dependency or a wavelength dependency, such as a dielectric mirror formed by laminating dielectric thin films having different refractive indexes, and selectively reflects or transmits a reflection layer or semi-transmissive reflection. Is a layer. Regarding the wavelength or frequency of incident light from the transparent substrate 41 side, the transmittance of the reflective layer when transmitting from the transparent substrate 41 side toward the near-field light generating unit 1 side (that is, the upper side in FIG. 8) is the opposite. It is higher than the transmittance when transmitting from the near-field light generator 1 side toward the transparent substrate 41 side (that is, the lower side in FIG. 8), for example, a value of 50% or more. From the viewpoint of the utilization efficiency of incident light, the higher the transmittance value here, the better.

  Furthermore, with respect to the wavelength or frequency of the near-field light, the reflectance of the reflective layer 42 when reflecting the near-field light toward the near-field light generating unit 1 side (that is, the upper side in FIG. 8) Reflected toward the transparent substrate 41 side when near-field light is incident from the transparent substrate 41 side instead of the reflectance when reflecting toward the side (ie, the lower side in FIG. 8) or virtually incident light. For example, the value is 50% or more. From the viewpoint of utilization efficiency of near-field light, the higher the reflectance value here, the better.

  Therefore, the incident light guided by the transparent substrate 41 is directed from the transparent substrate 41 side to the near-field light generating unit 1 side by the reflective layer 42 disposed between the transparent substrate 41 and the near-field light generating unit 1. Transparent. That is, the near-field light generator 1 can obtain energy necessary for generating near-field light from incident light that is transmitted through the reflective layer 42 and incident.

  On the other hand, the component that is generated by the near-field light generating unit 1 (not the component that directly proceeds to the output end side) and returns to the transparent substrate 41 side is between the transparent substrate 41 and the near-field light generating unit 1. Is reflected toward the near-field light generating unit 1 side by the reflecting action of the reflecting layer 42 disposed in the area. That is, a component that tends to return to the transparent substrate 41 side (that is, toward the lower side in FIG. 8) also proceeds to the output end side (that is, toward the upper side in FIG. 8) due to the reflection action in the reflective layer 42. It becomes possible to change to.

  Therefore, compared with the case where the reflective layer 42 does not exist, the near-field light component that returns to the transparent substrate 41 side or diverges from the output end (without being output to the outside) is Remarkably reduced.

  As described above in detail, according to the fourth embodiment, it is possible to dramatically improve the energy efficiency by mainly using the reflective layer 42.

  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 near-field light accompanying such a change. The device and the manufacturing method thereof are also included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Near field light generation part, 11 ... Light source, 12 ... Transparent substrate, 13 ... GaAs buffer layer, 14 ... InAs layer, 15 ... GaAs layer, 16 ... InAs quantum dot, 17 ... Metal edge, 17b ... Quantum dot, 20 DESCRIPTION OF SYMBOLS ... Light source, 21 ... Transparent substrate, 22 ... Antenna layer, 31 ... Metal nanoparticle, 32 ... Protective layer, 34 ... Tapered part, 30 ... Glass substrate, 35 ... Waveguide, 36 ... Grating, 40 ... Light source, 41 ... Transparent Substrate, 42 ... reflective layer, 100 ... near-field light device, 300 ... near-field light device, 350 ... near-field light device, 400 ... near-field light device

Claims (4)

A substrate,
A quantum dot layer, disposed on the substrate, including a first quantum dot, capable of generating first near-field light by light generation action of the first quantum dot using incident light guided by the substrate as an energy source; ,
A second near field is disposed on the quantum dot layer, includes a second quantum dot, and generates a second near field by the light generation action of the second quantum dot using the first near field light generated in the quantum dot layer as an energy source. A near-field light device comprising: an output end capable of generating light and outputting to the outside. A substrate,
A quantum dot layer disposed on the substrate, including quantum dots, capable of generating near-field light by light generation action of the quantum dots using incident light guided by the substrate as an energy source; and
An output end that is disposed on the quantum dot layer and capable of outputting the near-field light generated in the quantum dot layer to the outside;
An energy concentrating layer disposed between the substrate and the quantum dot layer and concentrating the energy of the guided incident light toward at least one of the quantum dot layer and the output end. Features near-field optical device. A substrate,
The near-field light is arranged on the substrate and can generate near-field light using incident light guided by the substrate as an energy source, and the generated near-field light is output from the output end facing the opposite side of the substrate to the outside. A near-field light generator capable of output, and
The near-field light generating unit includes a protective layer and a plurality of metal nanoparticles that are discretely arranged in the protective layer and each function as a quantum dot,
The near-field light device, wherein the protective layer is provided with a taper so that the outer shape of the protective layer becomes narrower from the substrate side toward the output end side. A substrate,
The near-field light is arranged on the substrate and can generate near-field light using incident light guided by the substrate as an energy source, and the generated near-field light is output from the output end facing the opposite side of the substrate to the outside. A near-field light generator capable of output;
The near-field light generating unit is disposed between the substrate and the near-field light generating unit, and transmits the guided incident light from the substrate side toward the near-field light generating unit. A near-field light device comprising: a reflection layer that reflects the generated near-field light toward the near-field light generation unit.