JP2015185874A - electromagnetic wave propagation medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic wave propagation medium of a high refractive index of 3.5 or greater.SOLUTION: An electromagnetic wave propagation medium comprises: positive refractive index layers and negative index layers arranged such that one alternates with the another, the positive refractive index layer containing an electromagnetic response element 1 that applies a positive refractive index by the collection of structures in which electric dipoles or magnetic dipoles are passively induced in response to an arriving electromagnetic wave, the negative refractive index layer containing an electromagnetic response element 2 that applies a negative refractive index. In a case where an arriving electromagnetic wave is made incident on the one end face of the electromagnetic wave propagation medium in the direction of its thickness, passes through the positive refractive index layer and negative refractive index layer, and reaches the other end face of the electromagnetic wave propagation medium in the direction of its thickness, the absolute value of an effective refractive index ne calculated from a Snell principle based on a refractive angle θe formed between a straight line (a short circuit approximation path) connecting an incident point on the one end face of the electromagnetic wave propagation medium and an arrival point on the other end face and based on the incident angle θ0 of an arriving electromagnetic wave, is larger than the absolute value of the refractive index n1 of the positive refractive index layer containing the electromagnetic response element 1 and that of the refractive index n2 of the negative refractive index layer containing the electromagnetic response element 2.

Description

  The present invention relates to a left-handed propagation medium (metamaterial) that is an assembly of artificial electric dipoles, magnetic dipoles, or composites thereof (hereinafter referred to as electromagnetic response elements) and a normal right-handed propagation medium. In particular, the present invention relates to an electromagnetic wave propagation medium in which the absolute value of the refractive index is larger than the refractive index of each of the left-handed and right-handed propagation media that are constituent elements.

  Resonating a split ring resonator in a desired frequency band with respect to constructing an electromagnetic wave propagation medium called negative refractive index medium, left-handed propagation medium or metamaterial by arranging artificial electromagnetic response elements Therefore, Patent Document 1 discloses a configuration that can exhibit a negative refractive index in the vicinity of the frequency band. In FIGS. 13 and 14 of Patent Document 2, a negative refractive index medium using a photonic crystal is disclosed.

  2 and 4 of Patent Document 2 disclose a structure in which a plurality of negative refractive index medium layers and a normal positive refractive index medium (right-handed electromagnetic wave propagation medium) layer are alternately stacked.

  However, since the laminated structure described in Patent Document 2 is intended to obtain an imaging effect, it has not been recognized as a problem to obtain a high refractive index, and accordingly, a positive refractive index and a negative refractive index are combined. There is no suggestion or disclosure about the possibility of obtaining a high refractive index as a whole of the laminated structure by acting in a functional manner.

  Patent Document 3 and Patent Document 4 disclose a two-layer structure of a metamaterial (left-handed electromagnetic wave propagation medium) layer and a normal substance (right-handed electromagnetic wave propagation medium) layer, and further combining the two layers. It is not limited to the two-layer structure, and it is mentioned that a gradient composition type composite structure in which a plurality of layers are alternately laminated or the density of electromagnetic response elements is gradually changed to form a clear layer boundary may be used.

  However, since the laminated structure described in Patent Document 3 is intended to obtain an interference effect, the thickness of the entire laminated structure is limited to an integral multiple of ½ wavelength in the propagation electromagnetic wave, There is no provision for the thickness of each layer. In addition, the electromagnetic wave propagation medium described in Patent Document 3 has a problem of keeping the intensity of interference caused by interface reflection at a certain level or more over a wide frequency band. Patent Document 3 discloses that an electromagnetic wave is a left-handed electromagnetic wave. The propagation distance formed by adding the distance passing through the propagation medium layer and the distance passing through the right-handed electromagnetic wave propagation medium layer is kept constant with respect to a frequency band having a certain width. It is only described that the interference intensity is kept constant, and it has not been recognized as a problem to obtain a high refractive index, and therefore a high refractive index is obtained by combining positive and negative refractive indexes. There is no suggestion or disclosure about the possibility of obtaining

  Another object of the electromagnetic wave propagation medium described in Patent Document 4 is to maintain the intensity of interference caused by interface reflection at a certain level or more over a wide frequency band. Propagation distance formed by adding the distance passing through the medium layer and the distance passing through the right-handed electromagnetic wave propagation medium layer is kept constant for a frequency band with a certain width, and the interference between the incident wave and the reflected wave in that frequency band It is described that the strength is also kept constant. In addition, Patent Document 4 aims to limit the reflection direction of the reflected wave to a narrow angle close to the incident direction, and solves this by utilizing negative direction reflection at the interface between the left-handed electromagnetic wave propagation medium layer and the metal reflector. It is described to do. That is, even in Patent Document 4, obtaining a high refractive index is not recognized as a problem, and therefore, the possibility of obtaining a high refractive index by combining positive and negative refractive indexes is also disclosed. It has not been done.

  By the way, what is called an artificial dielectric or a pseudo dielectric is known as a structure that artificially enhances electromagnetic responsiveness. Whereas a normal dielectric material is a collection of minute electric dipoles due to a slight displacement of ions (for example, 0.1 nm or less), an artificial dielectric has a large polarization such as a metal wire having a length of 1000 nm or more. It is possible to obtain a high dielectric constant by arranging a large number of electric dipoles capable of satisfying the requirements. The magnetic response is not particularly enhanced and high permeability cannot be obtained, so the degree of change in refractive index is limited. Usually, the artificial dielectric or pseudo-dielectric is a right-handed electromagnetic wave propagation medium.

If a lens is manufactured using a material having a high refractive index, a large numerical aperture can be obtained with a small curvature. For this reason, it is possible to provide a thin and lightweight lens in applications that require light collection from a wide angle range and applications that require light diffusion in a wide angle range. As a substance having transparency to an electromagnetic wave having a wavelength of visible light or a wavelength close to it suitable for such a purpose and having a high refractive index n, diamond (refractive index n = 2.42), rutile (refractive index). n = 2.62-2.90), germanium (refractive index n = 3.07), arsenic selenide: As ₂ Se ₃ (refractive index n = 3.15) and the like are generally known. However, no high refractive index material having a refractive index exceeding 3.5 has been found.

JP 2011-254482 A Japanese Patent Application No. 2006-215544 JP 2012-089785 A Japanese Patent Application No. 2012-090225

  The present invention has been made paying attention to such problems, and the object of the present invention is to provide an electromagnetic wave propagation medium having a high refractive index having a refractive index of 3.5 or more.

That is, the invention according to claim 1
An electromagnetic response element 1 that gives a positive refractive index by aggregating structures (hereinafter referred to as “electromagnetic response elements”) in which electric dipoles or magnetic dipoles are passively induced in response to incoming electromagnetic waves. An electromagnetic wave propagation medium comprising: a positive refractive index layer including a negative refractive index layer including an electromagnetic response element that gives a negative refractive index when the electromagnetic response elements are aggregated; When electromagnetic waves are incident on one end surface in the thickness direction of the electromagnetic wave propagation medium and reach the other end surface in the thickness direction of the electromagnetic wave propagation medium through at least one positive refractive index layer and at least one negative refractive index layer. Snell based on the refraction angle (effective refraction angle) θe formed by the straight line (short-circuit approximation path) connecting the incident point on the one end surface and the arrival point on the other end surface of the medium and the incident angle θ0 of the incoming electromagnetic wave Calculated from the law of The absolute value of the refractive index (effective refractive index) ne is larger than the absolute value of the refractive index n1 of the positive refractive index layer including the electromagnetic response element 1 and the refractive index n2 of the negative refractive index layer including the electromagnetic response element 2 It is characterized by having
The invention according to claim 2
The electromagnetic wave propagation medium according to claim 1,
The absolute value of the refractive index (effective refractive index) ne is 3.5 or more,
The invention according to claim 3
The electromagnetic wave propagation medium according to claim 1 or 2,
The positive refractive index layer is composed of a thin layer in which fine rutile powder is dispersed in a resin, and the negative refractive index layer is a thin film in which resin pieces having a split ring-shaped fine metal pattern formed on the surface are dispersed in the resin. It is characterized by comprising layers.

The invention according to claim 4
The electromagnetic wave propagation medium according to claim 1, 2, or 3,
The density of the electromagnetic response element 1 in the positive refractive index layer or the electromagnetic response element 2 in the negative refractive index layer changes alternately in the thickness direction,
The invention according to claim 5
The electromagnetic wave propagation medium according to claim 1, 2, or 3,
The density of the electromagnetic response element 1 in the positive refractive index layer or the electromagnetic response element 2 in the negative refractive index layer varies alternately and continuously over the thickness direction,
The invention according to claim 6
The electromagnetic wave propagation medium according to claim 1, 2, or 3,
The thickness of each of the positive refractive index layer and the negative refractive index layer is smaller than a quarter wavelength in the propagating electromagnetic wave.

Next, the invention according to claim 7 provides:
The electromagnetic wave propagation medium according to claim 1, 2, 3, 4 or 5,
The distribution center position of the electromagnetic response element 1 in the positive refractive index layer or the negative refractive index layer in which the density changes alternately, and the electromagnetic response element 2 or positive refractive index layer in another adjacent negative refractive index layer The distance from the distribution center position of the electromagnetic response element 1 is smaller than ¼ wavelength in the propagating electromagnetic wave,
The invention according to claim 8 provides:
The electromagnetic wave propagation medium according to claim 1, 2, 3, 4, 5 or 6,
The thickness of the positive refractive index layer and the thickness of the negative refractive index layer are not equal throughout the laminated structure,
The invention according to claim 9 is:
In the electromagnetic wave propagation medium according to claim 1, 2, 3, 4, 5 or 7,
The distribution center position of the electromagnetic response element 1 in the positive refractive index layer or the negative refractive index layer in which the density changes alternately, and the electromagnetic response element 2 or positive refractive index layer in another adjacent negative refractive index layer The distance from the distribution center position of the electromagnetic response element 1 is not equal throughout the laminated structure.

According to the electromagnetic wave propagation medium according to the present invention,
Based on the refraction angle (effective refraction angle) θe formed by the straight line (short-circuit approximation path) connecting the incident point on one end surface and the arrival point on the other end surface in the electromagnetic wave propagation medium, and the incident angle θ0 of the incoming electromagnetic wave The absolute value of the refractive index (effective refractive index) ne calculated from Snell's law is the refractive index n1 of the positive refractive index layer including the electromagnetic response element 1 and the refractive index n2 of the negative refractive index layer including the electromagnetic response element 2. It has a value greater than the absolute value.

  Therefore, it has an effect that can be used as an electromagnetic wave propagation medium exhibiting a high refractive index.

The schematic perspective view which showed typically the structure of the conventional split ring resonator. Explanatory drawing which showed typically the propagation path of the electromagnetic wave in the electromagnetic wave propagation medium based on this invention formed by laminating | stacking a positive refractive index layer and a negative refractive index layer alternately. FIG. 3 is an explanatory diagram schematically showing an electromagnetic wave propagation medium according to the present invention in which positive refractive index layers and negative refractive index layers are alternately stacked, with a refractive index distribution in a cross section thereof. 4 is a graph showing the relationship between the value of the refractive index n1 in the positive refractive index layer and the value of the effective refractive index ne of the electromagnetic wave propagation medium for the electromagnetic wave propagation medium according to the present invention shown in FIG. Explanatory drawing which showed typically by distribution of the refractive index in the cross section about the electromagnetic wave propagation medium which concerns on Example 1 formed by laminating | stacking a positive refractive index layer and a negative refractive index layer alternately. The graph which showed the relationship between the value of the refractive index n1 in the positive refractive index layer, and the value of the effective refractive index ne of an electromagnetic wave propagation medium about the electromagnetic wave propagation medium which concerns on Example 1. FIG. Explanatory drawing which showed typically by distribution of the refractive index in the cross section about the electromagnetic wave propagation medium which concerns on Example 2 formed by laminating | stacking a positive refractive index layer (vacuum) and a negative refractive index layer alternately. For the electromagnetic wave propagation medium according to Example 2 formed by alternately laminating a positive refractive index layer (vacuum) and a negative refractive index layer, the value of the refractive index n2 in the negative refractive index layer and the effective refractive index ne of the electromagnetic wave propagation medium The graph which showed the relationship with a value. Explanatory drawing which showed typically by distribution of the refractive index in the cross section about the electromagnetic wave propagation medium which concerns on Example 3 formed by laminating | stacking a positive refractive index layer and a negative refractive index layer alternately. Explanatory drawing which showed typically by the density distribution of the electromagnetic response elements 1 and 2 in the cross section about the electromagnetic wave propagation medium which concerns on Example 4 formed by laminating | stacking a positive refractive index layer and a negative refractive index layer alternately. Explanatory drawing which showed typically the example of application of the flat lens by the electromagnetic wave propagation medium which exhibits a high refractive index.

  Hereinafter, embodiments according to the present invention will be described in detail.

1. Configuration of Electromagnetic Wave Propagation Medium According to the Present Invention The electromagnetic wave propagation medium according to the present invention is configured by alternately laminating “positive refractive index layers” and “negative refractive index layers”.

  The “positive refractive index layer” is formed by aggregating structures (hereinafter referred to as “electromagnetic response elements”) in which electric dipoles or magnetic dipoles are passively induced in response to incoming electromagnetic waves. The electromagnetic response element 1 that gives a refractive index is included, and the “negative refractive index layer” includes an electromagnetic response element 2 that gives a negative refractive index by the electromagnetic response elements being assembled.

  In addition, the thickness of each of the “positive refractive index layer” and the “negative refractive index layer” is set to be smaller than ¼ wavelength in the propagating electromagnetic wave, and more desirably smaller than 1/10 wavelength in the propagating electromagnetic wave. Is set.

  When the thickness of each of the “positive refractive index layer” and the “negative refractive index layer” is larger than ¼ wavelength in the propagating electromagnetic wave, multiple reflections at the interface of each layer interfere with each other, and the electromagnetic wave propagation medium for the incident electromagnetic wave This is because the reflectivity as a whole increases, and at the same time, the transmittance greatly decreases, and the utilization of the electromagnetic waves collected from a wide angle may be hindered to decrease. However, even if the reflection as a whole of the electromagnetic wave propagation medium becomes dominant, it is possible to partially prevent the collected electromagnetic waves from being separated by the confinement effect described later.

  When the thickness of each of the “positive refractive index layer” and the “negative refractive index layer” is smaller than a quarter wavelength in the propagating electromagnetic wave, the phase between multiple reflections at the interface of each layer approaches, causing strong interference with each other. Therefore, it is possible to avoid a significant decrease in the transmittance of the entire electromagnetic wave propagation medium with respect to the incident electromagnetic wave.

  Furthermore, if the thickness of each of the “positive refractive index layer” and the “negative refractive index layer” is smaller than 1/10 wavelength in the propagating electromagnetic wave, the phases between the multiple reflections at the interface of each layer become closer to each other, so Interference does not occur, the action as a substantially continuous medium in which the characteristics of the layers are combined is dominant, and a decrease in transmittance due to interface reflection is further suppressed.

  As another method for suppressing multiple reflections at the interface of each layer, the concentration of the electromagnetic response element 1 that gives a positive refractive index by aggregation and the concentration of the electromagnetic response element 2 that gives a negative refractive index by aggregation. Is a graded composition type laminated structure that does not gradually change to form a clear layer boundary.

  Furthermore, another method for reducing the adverse effects caused by the multiple reflection at the interface of each layer is to make the thickness of each layer of the multilayer structure unequal.

  For the “negative refractive index layer”, for example, the split ring resonator disclosed in Patent Document 1 (that is, a resin piece having a split ring-shaped fine metal pattern formed on the surface) is integrated and dispersed in the resin. It can be formed by a thin layer. FIG. 1 schematically shows the form of a split ring resonator, and it can be used as an actual propagation medium by three-dimensionally arranging it as shown in FIG. It is desirable that the size of the split ring, which is a component, be sufficiently smaller (generally 1/10 or less) than the wavelength of the propagating electromagnetic wave.

  The “positive refractive index layer” can be formed, for example, by a thin layer in which fine rutile powder is dispersed in a resin.

2. Operation of the Electromagnetic Wave Propagation Medium According to the Present Invention Hereinafter, the “positive refractive index layer” including the electromagnetic response element 1 that gives a positive refractive index when the electromagnetic response elements are aggregated and the electromagnetic response elements are negative when the electromagnetic response elements are aggregated. The action of the electromagnetic wave propagation medium according to the present invention in which “negative refractive index layers” including the electromagnetic response element 2 that gives the refractive index of FIG. 2 are alternately laminated will be specifically described based on the example shown in FIG.

  For simplification of the figure and description, FIG. 2 shows a case where the uppermost layer and the lowermost layer are both composed of the electromagnetic response element 1, but the following description is not limited to this layer configuration, and the generality is Maintained.

  As shown in FIG. 2, an electromagnetic wave arriving from the atmosphere is incident on a point (incidence point O) on one end surface (uppermost layer) in the thickness direction of the electromagnetic wave propagation medium according to the present invention, and is refracted at each layer boundary. When a point (arrival point P) on the other end surface (lowermost layer) in the thickness direction is reached via the path, a propagation path that becomes a fine broken line (shown by a solid line in FIG. 2) in the electromagnetic wave propagation medium is an incident point O It can be approximated by a short circuit approximate path OP indicated by a broken line connecting the arrival points P. Further, the angle formed by the short-circuit approximate path OP and the incident axis (perpendicular to the incident end face) can be defined as the effective refraction angle θe.

  Consider a coordinate system in which the incident point is the origin O (0, 0) and the x axis is in the incident end face in a plane including propagation paths in the atmosphere and in the electromagnetic wave propagation medium. Assuming that the incoming electromagnetic wave propagates through the first quadrant, the coordinates (Px, Py) of the arrival point P in the third or fourth quadrant are as shown in the following formulas (1) and (2). .

Px =-(t1 '· tanθ1 + t2' · tanθ2) (1)
Py =-(t1 '+ t2') (2)

However, the refraction angle of the electromagnetic wave incident from the “positive refractive index layer” including the electromagnetic response element 1 to the “negative refractive index layer” including the electromagnetic response element 2 is θ2 (hereinafter, the sign of θ is the incident in the incident layer) Clockwise with respect to the vertical axis passing through the point, and counterclockwise as negative)
The refraction angle of the electromagnetic wave incident from the “negative refractive index layer” including the electromagnetic response element 2 to the “positive refractive index layer” including the electromagnetic response element 1 is θ1,
The total thickness of the “positive refractive index layer” including the electromagnetic response element 1 is t1 ′,
The total thickness of the “negative refractive index layer” including the electromagnetic response element 2 was defined as t2 ′.

The effective refraction angle θe formed by the short-circuit approximation path OP and the incident axis (perpendicular to the incident end face) is
θe = tan ^-1 (Px / -Py) (3)
And
Using this, the effective refractive index ne of the electromagnetic wave propagation medium calculated from "Snell's Law" is
ne / n0 = sinθ0 / sinθe (4)
It becomes.

  Here, the refractive index of the atmosphere is n0, and the incident angle of the incoming electromagnetic wave at the incident point O is θ0.

  θe → 0, that is, Px → 0 according to Equation (3), ne → ∞.

The positive refractive index of the “positive refractive index layer” including the electromagnetic response element 1 is n1,
When the negative refractive index of the “negative refractive index layer” including the electromagnetic response element 2 is n2,
From the above formula (4) and formula (3),
ne = n0 · sinθ0 / sinθe
= Sinθ0 / sin {tan ^-1 (Px / -Py)} (5)

Further, by substituting the formulas (1) and (2) into the formula (5),
ne = n0 · sin θ0 / sin {tan ⁻¹ (Px / −Py)}
= N0 · sinθ0 / sin {tan ^-1 [-(t1 '· tanθ1 + t2' · tanθ2)
/ (t1 '+ t2')]} (6)

And from "Snell's Law"
Since n0 ・ sinθ0 = n1 ・ sinθ1 = n2 ・ sinθ2,
θ1 = sin ^-1 (n0 · sinθ0 / n1) (7)
θ2 = sin ^-1 (n0 · sinθ0 / n2) (8)

That is, by substituting Equation (7) and Equation (8) into Equation (6),
ne = n0 · sinθ0 / sin {tan ^-1 [-(t1 '· tan (sin ^-1 (n0 · sinθ0 / n1)))
+ T2 '· tan (sin ^-1 (n0 · sinθ0 / n2)) / (t1' + t2 ')]} (9)
It is expressed.

  As an example, “positive refractive index layer” (thickness t1 = 1 μm, refractive index n1) and “negative refractive index layer” (thickness t2 = 1 μm, refractive index n2 = −1.7) of each layer alternately. FIG. 3 schematically shows the electromagnetic wave propagation medium according to the refractive index distribution in the cross section of the laminated electromagnetic wave propagation medium of the present invention.

  Then, with respect to incident light having an incident angle θ 0 = 45 ° (π / 4 rad) of the incoming electromagnetic wave at the incident point O shown in FIG. 2, when the refractive index n 2 of the “negative refractive index layer” is −1.7, The change in the effective refractive index ne of the electromagnetic wave propagation medium with respect to the change in the refractive index n1 in the “positive refractive index layer” is shown in the graph of FIG. 4 by substituting the incident angle θ0 and the refractive index n2 into (9).

  The absolute value of the effective refractive index ne of the electromagnetic wave propagation medium is greater than 3.5 for most values of the refractive index n1 shown in the figure. In particular, the refractive index n1 in the “positive refractive index layer” is In the region where the absolute value of the refractive index n2 in the “negative refractive index layer” is close, the absolute value of the effective refractive index ne shows an extremely large value of 10 or more due to the divergent behavior. For example, when n1 = 1.8, ne = 46.8, which is an extremely large value.

  When the thickness of each layer in the “positive refractive index layer” and the “negative refractive index layer” is very small compared to the wavelength of the propagating electromagnetic wave and can be regarded as an approximately homogeneous medium, it is shown in the above and FIG. Geometric optics considerations lack validity. However, also in this case, as the thickness of each layer decreases, ne becomes far from the value given by Equation (9), but at least until it can be regarded as a homogeneous medium, it has a finite refraction. A rate enhancement effect can be expected.

3. Effect of the electromagnetic wave propagation medium according to the present invention If a lens is manufactured using a substance having a high refractive index, a large numerical aperture can be obtained with a small curvature, and therefore, an application that requires condensing from a wide angle range, Even in applications that require light diffusion over a wide angular range, a thin and lightweight lens can be provided. In particular, when the refractive index can be regarded as substantially infinite, the curvature is zero, that is, a wide angle range from 0 degrees to almost 90 degrees is used while using a flat lens that does not require curved surface formation. Incident light can be condensed with the propagation direction aligned so as to propagate perpendicularly to the lens surface (see FIG. 11). The condensing action in this case works equally with incident light at any position on the flat lens. For example, if a large-area light-receiving element such as a solar battery cell is covered with this flat lens, the solar cell Incident light from the periphery can be guided to the entire light receiving surface. Unlike normal lenses that collect incident light in a narrow area near the focal position, it is possible to achieve uniform light collection on a large-area light-receiving surface, resulting in local overheating and thermal distortion. Thus, it is possible to keep the conversion efficiency and the service life of the light receiving element favorable.

  In addition, even if the light once collected is diffusely reflected on the surface of the light receiving element having a messy shape and returned to the lens side, for example, the light that reaches the lens / atmosphere interface at an angle receives total reflection and goes to the outside. It cannot be emitted. That is, a flat lens having an infinite refractive index also has an excellent light confinement effect.

  For example, if light emitted from a laser element limited to a very narrow angle range is guided perpendicularly to the lens / atmosphere interface, the light emitted into the atmosphere avoiding the total reflection condition has an emission angle of 0 degrees to almost 90 degrees. It will diffuse over a wide range of angles until it reaches degrees. In other words, a flat lens with an infinite refractive index is excellent as a means for uniformly diffusing a light beam having high energy and high straightness, such as a laser beam, over a wide angle range. This can be used not only for efficient diffusion of display light and illumination light, but also as an effect on decoration and design.

  Examples of the present invention will be specifically described below.

[Example 1]
FIG. 5 is an explanatory view schematically showing the refractive index distribution in the cross section of the electromagnetic wave propagation medium according to Example 1 in which positive refractive index layers and negative refractive index layers are alternately stacked.

  Conducted by alternately laminating the “negative refractive index layer” including the electromagnetic response element 2 and the “positive refractive index layer” including the electromagnetic response element 1 with the refractive index adjusted to “−1.7” for the electromagnetic wave having a wavelength of 5 μm. The electromagnetic wave propagation medium according to Example 1 is configured.

  The thickness t1 of the “positive refractive index layer” is 1 μm, the thickness t2 of the “negative refractive index layer” is 1.5 μm, and the refractive index n1 of the “positive refractive index layer” for electromagnetic waves with a wavelength of 5 μm is changed from “1” to “1”. When set to 2.5 ", the effective refractive index ne of the electromagnetic wave propagation medium shows a large absolute value of" 2.5 or more "as shown in FIG. 6, and particularly when n1 = 1.3, ne = 46. A large value of 7 is obtained.

  The “negative refractive index layer” including the electromagnetic response element 2 can be formed, for example, by appropriately dispersing a resin piece on the surface of which a split ring-shaped fine metal pattern is formed. In addition, the “positive refractive index layer” including the electromagnetic response element 1 can be formed, for example, by appropriately dispersing fine rutile powder in a resin.

[Example 2]
FIG. 7 is an explanatory view schematically showing an electromagnetic wave propagation medium according to Example 2 formed by alternately laminating positive refractive index layers (vacuum layers) and negative refractive index layers according to the refractive index distribution in the cross section. .

  That is, a “negative refractive index layer” having a thickness of 1.0 μm including the electromagnetic response element 2 is arranged in a vacuum through a constant interval (1.0 μm), and the refractive index n1 is “ The electromagnetic wave propagation medium according to Example 2 is configured by alternately laminating “positive refractive index layer” (vacuum layer) that is “1” and “negative refractive index layer” having a thickness of 1.0 μm.

  When the refractive index n2 of the “negative refractive index layer” for electromagnetic waves with a wavelength of 10 μm is set from “−1” to “−2.5”, the effective refractive index ne of the electromagnetic wave propagation medium is as shown in FIG. A large absolute value of “−2 or less” is shown. In particular, when n 2 = −1.1, a large absolute value of ne = −8.8 is obtained.

  The “negative refractive index layer” including the electromagnetic response element 2 can be formed, for example, by appropriately dispersing a resin piece on the surface of which a split ring-shaped fine metal pattern is formed.

[Example 3]
FIG. 9 is an explanatory diagram schematically showing the refractive index distribution in the cross section of the electromagnetic wave propagation medium according to Example 3 formed by alternately laminating positive refractive index layers and negative refractive index layers.

  However, unlike Example 1, the density of the electromagnetic response element 1 in the “positive refractive index layer” and the density of the electromagnetic response element 2 in the “negative refractive index layer” are alternately changed in the thickness direction, and “ Since the interface is obscured by changing the absolute value of the refractive index in the vicinity of the boundary between the “positive refractive index layer” and the “negative refractive index layer”, the interface reflection can be suppressed as compared with the first embodiment. it can.

  The “negative refractive index layer” including the electromagnetic response element 2 can be formed, for example, by appropriately dispersing a resin piece having a split ring-shaped fine metal pattern on the surface thereof in the resin. The “positive refractive index layer” containing can be formed, for example, by appropriately dispersing fine rutile powder in a resin.

[Example 4]
FIG. 10 is an explanatory view schematically showing the electromagnetic wave propagation medium according to Example 4 formed by alternately laminating positive refractive index layers and negative refractive index layers by the density distribution of electromagnetic response elements 1 and 2 in the cross section. .

  That is, a region of “positive refractive index layer” mainly composed of electromagnetic response element 1 and a region of “negative refractive index layer” mainly composed of electromagnetic response element 2 are alternately laminated. Since the electromagnetic response element 1 and the electromagnetic response element 2 are mixed and the interface is unclear, the interface reflection can be suppressed as in the third embodiment.

  The “negative refractive index layer” including the electromagnetic response element 2 can be formed by, for example, appropriately dispersing a resin piece having a split ring-shaped fine metal pattern on the surface thereof in the resin. The “positive refractive index layer” can be formed, for example, by appropriately dispersing fine rutile powder in the resin, and the coating liquid constituting the “negative refractive index layer” and “ It is applied so that the coating liquid constituting the “positive refractive index layer” is mixed.

  Since the electromagnetic wave propagation medium according to the present invention can be used as an electromagnetic wave propagation medium exhibiting a high refractive index, it has industrial applicability applied to lenses capable of condensing and diffusing at a wide angle. Yes.

Claims (9)

  An electromagnetic response element 1 that gives a positive refractive index by aggregating structures (hereinafter referred to as “electromagnetic response elements”) in which electric dipoles or magnetic dipoles are passively induced in response to incoming electromagnetic waves. An electromagnetic wave propagation medium comprising: a positive refractive index layer including a negative refractive index layer including an electromagnetic response element that gives a negative refractive index when the electromagnetic response elements are aggregated; When electromagnetic waves are incident on one end surface in the thickness direction of the electromagnetic wave propagation medium and reach the other end surface in the thickness direction of the electromagnetic wave propagation medium through at least one positive refractive index layer and at least one negative refractive index layer. Snell based on the refraction angle (effective refraction angle) θe formed by the straight line (short-circuit approximation path) connecting the incident point on the one end surface and the arrival point on the other end surface of the medium and the incident angle θ0 of the incoming electromagnetic wave Calculated from the law of The absolute value of the refractive index (effective refractive index) ne is larger than the absolute value of the refractive index n1 of the positive refractive index layer including the electromagnetic response element 1 and the refractive index n2 of the negative refractive index layer including the electromagnetic response element 2 An electromagnetic wave propagation medium characterized by comprising:   2. The electromagnetic wave propagation medium according to claim 1, wherein an absolute value of the refractive index (effective refractive index) ne is 3.5 or more.   The positive refractive index layer is composed of a thin layer in which fine rutile powder is dispersed in a resin, and the negative refractive index layer is a thin film in which resin pieces having a split ring-shaped fine metal pattern formed on the surface are dispersed in the resin. The electromagnetic wave propagation medium according to claim 1, wherein the electromagnetic wave propagation medium is configured by a layer.   The electromagnetic wave according to claim 1, 2, or 3, wherein the density of the electromagnetic response element 1 in the positive refractive index layer or the density of the electromagnetic response element 2 in the negative refractive index layer changes alternately in the thickness direction. Propagation medium.   The density of the electromagnetic response element 1 in the positive refractive index layer or the electromagnetic response element 2 in the negative refractive index layer changes alternately and continuously in the thickness direction. The electromagnetic wave propagation medium described.   4. The electromagnetic wave propagation medium according to claim 1, wherein the thickness of each of the positive refractive index layer and the negative refractive index layer is smaller than a quarter wavelength of the propagating electromagnetic wave.   The distribution center position of the electromagnetic response element 1 in the positive refractive index layer or the negative refractive index layer in which the density changes alternately, and the electromagnetic response element 2 or positive refractive index layer in another adjacent negative refractive index layer 6. The electromagnetic wave propagation medium according to claim 1, wherein a distance from a distribution center position of the electromagnetic response element 1 is smaller than a quarter wavelength of the propagation electromagnetic wave.   7. The electromagnetic wave propagation medium according to claim 1, wherein the thickness of the positive refractive index layer and the thickness of the negative refractive index layer are not equal throughout the laminated structure.   The distribution center position of the electromagnetic response element 1 in the positive refractive index layer or the negative refractive index layer in which the density changes alternately, and the electromagnetic response element 2 or positive refractive index layer in another adjacent negative refractive index layer The electromagnetic wave propagation medium according to claim 1, 2, 3, 4, 5 or 7, wherein the distance from the distribution center position of the electromagnetic response element 1 is not equal throughout the laminated structure.