KR102001151B1 - Invisibility apparatus and method thereof - Google Patents

Abstract

A transparency apparatus and method thereof are disclosed. A transparency apparatus according to an embodiment of the present invention is a transparency apparatus for transparency of a target object in a predetermined first region using a meta-material, the transparency apparatus comprising: A transparency unit; And a compensation unit that is disposed in a predetermined second region and is composed of a second metamaterial having a predetermined negative refractive index, the transparency unit is disposed so as to surround the first region and the second region, Is a negative refractive index for compensating the positive refractive index of the first region and making it transparent to the object.

Description

[0001] Invisibility apparatus and method [0002]

The present invention relates to a transparency apparatus and method thereof, and more particularly, to a transparency apparatus usable in an elliptical cylindrical coordinate system and a bipolar cylindrical coordinate system based on an isotropic complementary medium and a method thereof.

Recent research on meta-materials has enabled microscopic and macroscopic control of electromagnetic fields [Phys.Rev.Lett. 85, 3966 (2000); Science 312,1777 (2006); Science 312, 1780 (2006)). A metamaterial is an artificial method that can not be obtained in a normal natural state. An unusual point of a metamaterial is that it has a negative refractive index, so that the light in the metamaterial warps in the opposite direction .

Using these metamaterials, it was possible to adjust the direction of the electromagnetic field freely irrespective of the source of the electromagnetic field, and to guide the object as if there were no objects [Science 312, 1777 (2006); Science 312, 1780 (2006)). This can potentially be applied to radiation shielding from strong electromagnetic field pulses (EMP) or directional electromagnetic energy.

Electromagnetic field control using metamaterials has attracted great interest in the field of novel applications such as invisibility cloak, concentrator, and refractor.

Among them, the transparency cloak is the most attractive application by hiding objects inside a given geometric shape. Transparent cloaks are based on coordinate transformations and conformal mapping of the Maxwell equations. These translucent cloaks are based on Pentry [Science 312, 1780 (2006)] and Leonhardt [Science 312, 1777 (2006) ], Respectively.

Full-wave electromagnetic simulations of cylindrical cloaks using ideal or non-ideal electromagnetic parameters have been studied and experimental implementations of cylindrical cloaks with simple parameters operating at microwave frequencies have been published.

In analyzing and designing the transparency device, it is most important to calculate the dielectric constant tensor and the transmittance tensor for the metamaterial constituting the transparent shell.

The transparency device assumes that the field line will distort the field line so that it will move away from that area in some area having a uniform field line, which is considered to be a coordinate transformation between the original Cartesian mesh and the distortion mesh .

The theoretical and experimental implementations of such a conventional translucent device have been greatly influenced by the direction of the electromagnetic wave, the polarization, and the wavelength band. "Complementary media invisibility cloak that cloaks objects at a distance outside the cloaking shell," Y. Lai, H. Chen, Z. Q. Zhang, and C. Chan, Phys. Rev. Lett. 102,93901 (2009). (Publication Date 2009.03.02) proposed a technique for improving the efficiency of an invisible cloak using complementary media, but the prior art herself indicates that the prior art is effective at a finite frequency.

An attempt to overcome these limitations and extend them to applicable theories in a more general case is described in Doyeol Ahn, Journal of Modern Optics, Volume 58, Issue 8, 2011, entitled "Calculation of Permittivity Tensors for Invisibility Devices in General Relativity" (Published on April 21, 2011) and Korean Patent Laid-Open Publication No. 10-2013-0047860 (published on March 20, 2013).

This prior art approach can be scaled by the factors obtained by coordinate transformation or optical conformal mapping techniques while maintaining the form of the Maxwell's equation that does not change in any coordinate system.

In addition, methods of calculating permittivity tensors and permeability tensors for transparency devices using electrodynamics in the framework of the theory of relativity have also been studied.

The principle ideal of the prior art is based on the fact that the propagation of electromagnetic waves in a curved space-time appears as wave traveling in an inhomogeneous effective bi-anisotropic medium , Its constitutive parameters are determined by space-time metrics.

This can express the inverse problem of transforming from a flat space-time medium to a certain curvilinear space-time, and find specific conditions for invisibility cloaking.

This approach also has the advantage of being able to acquire the permittivity tensor and the transmittance tensor intuitively and directly for two- and three-dimensional inviscid devices, but with the exception of simple cylindrical and spherical forms, detailed calculations have not yet been made There is a problem.

However, in the prior art, there are many difficulties in realizing a transparent cloak in an actual three-dimensional space using an anisotropic medium.

Korean Patent Laid-Open Publication No. 10-2013-0047860 (Publication date 2013.05.09)

Doyeol Ahn, Journal of Modern Optics, Volume 58, Issue 8, 2011 (Publication date 2011.04.01) "Calculation of permittivity tensors for invisibility devices by effective medium approach in general relativity" "Complementary media invisibility cloak that cloaks objects at a distance outside the cloaking shell," Y. Lai, H. Chen, Z. Q. Zhang, and C. Chan, Phys. Rev. Lett. 102,93901 (2009). (Public date 2009.03.02)

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inversion apparatus and method that can be used in both an elliptical cylindrical coordinate system and a bipolar cylindrical coordinate system based on an isotropic compensation medium.

The present invention is based on the concept of a compensation medium and is based on a concept of compensating medium, which is a point-mapped and line-segment-mapped transparency apparatus with an isotropic compensation medium using both an elliptic cylindrical coordinate system and a bipolar cylindrical coordinate system, .

More specifically, the present invention relates to a transparency apparatus for improving transparency of a target object using a meta-material having a negative refractive index for compensating a positive refractive index of a region in which a target object is disposed, A method is provided.

It is another object of the present invention to provide a transparency apparatus and method which can make transparency of electromagnetic waves having arbitrary polarization and arbitrary traveling direction.

According to an aspect of the present invention, there is provided a transparency apparatus for transparency of a target object in a predetermined first region using a meta-material, the transparency apparatus comprising: A transparentizing unit surrounded by the first metamaterial; And a compensation unit which is disposed in a predetermined second region and is composed of a second metamaterial having a predetermined negative refractive index, and the transparency unit is arranged to surround the first region and the second region.

The negative refractive index may be a negative refractive index for transparency to the object by compensating the positive refractive index of the first region.

The compensation unit may be disposed in an area symmetrical with the area of the object, and may have a size the same as the size of the first area.

The first meta material may be designed by a concept of distorting the space between the first area and the second area with respect to electromagnetic waves so that the object becomes transparent.

The first meta material may be designed by applying an analysis technique in which the change of the traveling path of the electromagnetic wave due to the distortion of space-time surrounding the first area and the second area corresponds to the refractive index of the electromagnetic wave.

The first meta-material may be designed by interpreting Maxwell's equations for the bipolar coordinate system representing the first region and the second region.

The first meta-material may be designed by interpreting Maxwell's equations for an elliptical coordinate system representing the first region and the second region.

A transparency method according to an embodiment of the present invention is a transparency method for transparency of a target object within a predetermined first region using a meta-material, the transparency method comprising: Disposing the unit; And disposing a compensation unit, which is made up of a second metamaterial having a predetermined negative refractive index, in a second region predetermined to be adjacent to the first region in the transparency unit.

According to the present invention, by using a meta material having a negative refractive index to compensate a positive refractive index of a region in which a target object is disposed, transparency of the target object is improved, and an elliptical cylindrical coordinate system and a bipolar It is possible to improve transparency in various coordinate systems such as a cylindrical coordinate system.

Further, according to the present invention, by using a compensating meta-material having a negative refractive index for compensating the positive refractive index of a region in which a target object is disposed, it is advantageous that polarization can be made transparent in any direction other than a specific direction .

FIG. 1 shows an example of a transparent cloak based on a method for analyzing a space-time meta-material based on general relativity.
Figure 2 shows the spatial distribution of the configuration parameters of the elliptical cylindrical transparent cape and the bipolar cylindrical transparent cape.
3 shows a configuration of an elliptical cylindrical transparentizing apparatus (a) and a bipolar cylindrical transparentizing apparatus (b) according to an embodiment of the present invention.
Figure 4 shows the cloaking results for the elliptical cylindrical transparency apparatus of the present invention mapped to a point where the compensation medium is transversely positioned.
Figure 5 shows the results of cloaking for the elliptical cylindrical transparency apparatus of the present invention mapped to points when the compensation medium is vertically positioned.
Figure 6 shows the cloaking results for the elliptical cylindrical transparency apparatus of the present invention mapped to a line segment when the compensation medium is horizontally positioned.
Figure 7 shows the cloaking results for the elliptical cylindrical transparency apparatus of the present invention mapped to a line segment when the compensation medium is vertically positioned.
FIG. 8 shows the results of cloaking for an elliptical cylindrical transparency apparatus for making a quadrangular object placed inside thereof transparent by using a vertically arranged compensation medium.
FIG. 9 shows the results of cloaking for the bipolar cylindrical transparentizing apparatus of the present invention mapped to the? -Axis.
FIG. 10 shows the results of cloaking for a bipolar cylindrical transparentizing apparatus in which a rectangular object placed inside is made transparent using a vertically arranged compensation medium.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings.

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

However, the present invention is not limited to or limited by the embodiments. Like reference symbols in the drawings denote like elements.

Hereinafter, a transparentizing apparatus and method according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 10.

In this specification, a meta material is defined as follows. A metamaterial is used to mean a material that can artificially control or design the tensor of permittivity and permeability, or to be used as a material obtained as a result of its control or design.

When the Maxwell equations are formulated in a space-time with a finite curvature, the transparency device is based on the theoretical argument that the curvature of space-time acts as permittivity and permeability for electric and magnetic fields. do.

Specifically, the covariant Maxwell equation in the general relativity theory can be expressed by the following Equation (1).

&Quot; (1) "

Where ε ₀ is the permittivity in free space, μ, ν, and λ represent the permittivity of each component in the 4-dimensional coordinate space component.

g denotes a determinant of a metric tensor g _占 ., J denotes a current density, and F _{占 를} denotes an electromagnetic field tensor.

The above equation (1) can be expressed in Korean Patent Laid-Open Publication No. 10-2013-0047860 (published on May 31, 2013) and "Calculation of permittivity tensors for invisibility devices by effective medium approach in general relativity", Doyeol Ahn, Journal of Modern Optics , Volume 58, Issue 8, 2011 (Published on April 21, 2011).

Also, a derivation process for a plurality of equations derived from the following is also introduced in the prior art. Therefore, the present invention will be described in detail in the context of the present invention, without departing from the scope of the present invention.

At this time, the electromagnetic field tensor can be expressed by the following equation (2). Electromagnetic tensors are described in the form of matrices for three dimensions of zero dimension (time) and space in general relativity theory.

&Quot; (2) "

Here, E means electric field, x, y, z means direction, and B means electric flux.

The contra-variant tensor H? ^V can be expressed by the following Equation 3, and Equation 3 can be defined as Equation 4 below.

&Quot; (3) "

&Quot; (4) "

Here, H denotes a magnetic field and D denotes a magnetic flux.

If the above-described equations are summarized, the following equations (5) and (6) can be obtained.

Equation (5)

&Quot; (6) "

Here, [ijk] is an anti-symmetric permutation symbols (anti-symmetric permutation symbol), as defined in [xyz] = 1, μ ₀ denotes the permeability of free space, and g ^ab is the banbyeon metric tensor (a , b) component, and g _cd means (c, d) component of the covariance matrix tensor.

As can be seen from the above equation, it can be seen that the Maxwell's equation in a vacuum having a finite radius of curvature can be interpreted as a Maxwell's equation in a medium having a finite permittivity and transmittance.

FIG. 1 shows an example of a transparent cloak based on a method of analysis of space-time meta-materials based on general relativity. In the physical space, the middle empty space means a space for hiding a given object.

^' _ij로 정의하면 두 공간 사이의 변환식은 아래 수학식 7로 주어지며 메타 물질로 구현할 물리적 공간의 유전율 텐서(ε^ij)와 투과율 텐서(μ^ij)는 아래 수학식 8과 같이 표현될 수 있다.
The virtual space means a space in which an empty space of the physical space is converted into a central point. Using this relationship, we can create an intuitive picture of transparent cloak using coordinate transformations between the physical space and the virtual space to realize the actual invisibility cloaking, and between the two space-time. The coordinate transformation between these two spaces can be described by a space time metric tensor ( _gμν ), and a metric tensor representing the curvilinear coordinates of the physical space

^' _ij , the transformation between two spaces is given by Equation (7), and the permittivity tensor (ε ^ij ) and the permeability tensor (μ ^ij ) of the physical space to be implemented by the meta-material can be expressed by Equation (8) below.

&Quot; (7) "

&Quot; (8) "

는

_ij를 의미하고,

^kk는 1/

_kk를 의미한다.
here,

The

_ij means,

^kk is 1 /

_respectively .

However, the transparent cape implemented in this way has a disadvantage that the efficiency of transparency is maximized when the electromagnetic wave is polarized in a specific direction.

Thus, the present invention is directed to an apparatus and method that overcomes this disadvantage and is transparent to any polarization.

The present invention is based on papers already published by the inventors of the present invention [J. Mod. Opt. (2011), Journal of the Korean Physical Society 60, 1349-1360 (2012), JOSA B 30, 140-148 (2013)], and the target object is 0 <u <U ₁ , and the transparency device hides in the region U ₁ < u < U ₂ Lt; RTI ID = 0.0 &gt; meta-material &lt; / RTI &gt;

Using the primed coordinate for the empty curve time space, the physical medium can be defined as: &lt; EMI ID = 9.0 &gt; The coordinate system used here is a generalized cylindrical coordinate system such as a bipolar coordinate system.

&Quot; (9) &quot;

Here, U ₁ and U ₂ are predetermined values of a region made of a meta-material, u 'means a distance in a virtual space, u means a distance in a physical space, and v' Refers to the generalized angle or distance of the physical space, v denotes the generalized angle or distance in physical space, and z and z 'denote the distance (height) in physical space and z direction in virtual space.

Also, in general relativity theory, it is possible to obtain the configuration parameters for an elliptical cylindrical transparency device or a transparent clay as shown in Equation (10) from an effective medium approach.

&Quot; (10) &quot;

Where diag () denotes a diagonal matrix, and ε ⁱ _j and μ ⁱ _{j denote} the permittivity tensor and the permeability tensor in the elliptic cylindrical coordinate system.

2a and 2b show the spatial distribution of the constituent parameters of the elliptic cylindrical transparent cloak, wherein Fig. 2a is a constant value with 竜^u _u and 竜^v _v of 0.17 and 5.8, respectively, and the semi- ε ^z of an elliptic cylindrical cloak with a focal distance of 0.001 [m] (a = 0.001 m) and a half-length of the major axis of the ellipse with K ₁ and K ₂ of 0.1 and 0.3, respectively _z and Fig. 2b shows the spatial distribution of ε ^u _z of elliptic cylindrical clay with ε ^u _u and ε ^v _v of 0.75 and 1.3, respectively.

Here, the half-center distance and the half-center distance mean the degree of deviation from the cylinder, and the relation between K _i and U _i can be expressed by Equation (11) below.

Equation (11)

In the case of a bipolar cylindrical cloak, the area of the object to be hidden can be represented using a bipolar cylindrical coordinate system. The bipolar coordinate system is described by σ and τ as variables, and the description of σ and τ is described below.

At this time, the object to be hidden is placed in σ ₁ <σ <2π-σ ₁ , and the transparency apparatus is in the region {σ ₂ ≦ σ ≦ σ ₁ } ∪ {2π-σ ₁ ≦ σ ≦ 2π-σ ₂ }. Here,? Refers to an angle or a generalized distance in physical space, and? ₁ and? ₂ mean a predetermined angle or a generalized distance in physical space.

As a result, the map can be defined by the following equation (12).

&Quot; (12) &quot;

Here, σ 'denotes an angle in virtual space, σ denotes an angle in physical space, and τ and τ' denote angles σ and σ 'at a point P in the bipolar cylindrical coordinate system in physical space and virtual space to mean the ratio of the distance (d _1, d ₂₎ of the ', this is for information about the person of ordinary skill in the art bipolar coordinate system to engage in the art (https:.. // en wikipedia org / wiki / bipolar _ coordinates Etc.) and the relationship between the virtual space and the physical space in Fig. 1 can be easily understood.

Thus, the configuration parameters for the bipolar cylindrical transparency device or transparent cloak can be obtained as: &lt; EMI ID = 13.0 &gt;

&Quot; (13) &quot;

Where ε ⁱ _j and μ ⁱ _j are the permittivity tensor and the permeability tensor in a bipolar cylindrical coordinate system.

Fig. 2c shows the spatial distribution of the constituent parameters of the bipolar cylindrical transparent cloaca, where ε ^σ _σ and ε ^τ _τ are constant values of 0.5 and 2.0, respectively, and the half-center distance a is 0.3 [m] will have σ ₁ and σ ₂ shows the spatial distribution of the ε ^z _z of the bipolar cylindrical mantle having respective 0.75π, 0.5π, and Figure 2b is a constant value ε and ε ^u _u ^v _v is having a 0.75 and 1.3, respectively, The half-center distance (a) shows the spatial distribution of ε ^z _z of elliptic cylindrical clay with K ₁ and K ₂ of 0.1 and 0.3, respectively.

The most important point in designing the transparency apparatus of the present invention is that a perfect conductor (PEC) corresponding to 0 <u <U ₁ in the elliptic cylindrical cape and σ ₁ <σ <2π-σ ₁ in the bipolar cylindrical cape conductor region can be replaced by complementary media.

The compensating region, which can be replaced by the compensating material, can be divided into two symmetrical regions along the symmetry axis, one of the two symmetrical regions being filled with air, and the other region having both permittivity and transmittance - 1 &lt; / RTI &gt; isotropic complementary medium.

At this time, the isotropic compensation medium can have a both a permittivity and a transmittance of -1 according to the optical cancellation of the folding transformation (Appl. Phys. A 108,1001-1005 (2012)).

As shown in FIG. 3, the present invention provides a cloaking apparatus comprising: a cloaking shell made of a first metamaterial for transparentizing an object disposed in a first region; a cloaking shell disposed in a second region inside the first region, And a compensation unit (-1, -1) composed of a second meta material having a negative refractive index, for example, a permittivity and a transmittance both being -1.

That is, as can be seen from the elliptical cylindrical transparentizing apparatus shown in FIG. 3A and the bipolar cylindrical transparentizing apparatus shown in FIG. 3B, the positive refractive index (1, 1) By arranging a compensation medium having a negative refractive index (-1, -1) in a region symmetrical with the region having a refractive index, transparency can be improved and the configuration parameters of the compensation medium can be deduced.

3, the negative refractive index of the compensating medium constituting the compensating unit may be a negative refractive index for transparency to the object by compensating the positive refractive index of the first region, and the compensating unit may be a region symmetric with the region of the object, As shown in FIG.

Further, the compensation unit may be arranged to have the same size as the size of the object. Of course, regardless of the size of the object to be hidden, the compensation unit may determine the size and the area of the compensation unit in consideration of only the size corresponding to the positive refractive index area formed in the first area. That is, the size of the compensation unit corresponds to the size of the positive refractive index area, and the area to be arranged may be a region that is symmetrical to the area where the positive refractive index is formed.

The first meta material constituting the transparency unit may be designed so as to make the object transparent by distorting the space between the first area and the second area with respect to the electromagnetic wave. The first meta material may include a first area and a second area It can be designed by applying an analysis technique in which the change of the propagation path of the electromagnetic wave due to the distortion of space and time surrounding the wave is related to the refractive index of the electromagnetic wave.

The first meta-material may be designed by analyzing a Maxwell equation for a bipolar coordinate system representing a first region and a second region, and may be designed by interpreting Maxwell's equations for an elliptical coordinate system representing a first region and a second region It is possible.

Hereinafter, numerical results of the present invention will be described, and an elliptical cylindrical transparentizing apparatus and a bipolar cylindrical transparentizing apparatus having a compensation medium will be described.

1) elliptic cylindrical cloak with complementary media with compensation media

A two-dimensional elliptic cylindrical transparentizer is illuminated using both transverse electric (TE) (transverse electric) and polarized (TM) polarized plane waves with an operating frequency of 2 GHz (f = 2 GHz) and a wavelength of 15 cm

In this case, a finite-difference time-domain (FDTD) cell size of? X =? Y =? / 300 is used and a temporal discretization step is used to set the clamp stability, which is set to? T =? X / 2c ₀ (= 833.91 fsec) (Courant stability condition). The time identification step can be easily confirmed by a person skilled in the art who is skilled in the art by means of thesis search or the like and can be confirmed through, for example, "Electromagnetic simulation using the FDTD method"

In this case, c ₀ means the speed of light in vacuum.

First, the transparency device mapped to each point of the compensation medium is verified and the transparency device is calculated in the elliptic cylindrical coordinate system using the FDTD method.

In order to map the inviscid apparatus to a point, the half-sine parameter of the main axis of the inner ellipse K ₁ is 0.1 m, the half-sine parameter of the main axis of the outer ellipse K ₂ of 0.3 m and the parameter of the half-center distance (a) use.

The transparency device mapped to the points of the compensation medium shows very good cloaking results as shown in FIGS. 4 and 5.

Figures 4 and 5 illustrate the cloning results for the point-mapped elliptical cylindrical vitrification apparatus of the present invention with respect to the case where the compensation medium is horizontally positioned (Figure 4) and the compensation medium is positioned vertically (Figure 5) will be.

Figures 4a and 5a show all z components for the electric field distribution propagated along the positive x direction for the TE mode and Figures 4b and 5b show all z components for the electric field distribution propagated along the positive y direction for the TE mode, 4c and 5c show all z components for the magnetic field distribution propagated along the positive x direction for the TM mode and Figures 4d and 5d show all the z components for the TM As shown in FIGS. 4 and 5, the transparency apparatus according to the present invention can be applied to the TE mode and the TM mode, It can be seen that the cloaking results are excellent.

Secondly, mapping the transparency device with line segments with differently disposed compensation media and mapping the half-sine parameter of the major axis of the inner ellipse K ₁ to 0.1 m and the half-sine parameter and half-center distance of the major axis of the outer ellipse K ₂ of 0.3 m 0.09m is used. That is, only the half-center distance of the parameters used when mapping the transparency apparatus to points is long. This means that the inner space of the transparency device shrinks to a line segment.

Electro-magnetic waves from the outside are applied as line segments. If the inner space is filled with a perfect conductor (PEC), it becomes a PEC line segment. If the inner space is filled with the compensating medium, it becomes a compensation line segment. For this reason, the clocking performance is very different. PEC-filled elliptical cylindrical transparency device showed good cloaking performance only when the TM wave propagates along the positive x direction [Journal of the Korean Physical Society 60, 1349-1360 (2012)].

In contrast, in the present invention, it is important to compare the arrangement of the compensation media with respect to the clocking performance of the transparency apparatus mapped to a line segment in contrast to the transparency unit mapped to a single point.

FIGS. 6 and 7 show the results of cloaking for the elliptical cylindrical transparency apparatus of the present invention mapped to a line segment, with respect to the case where the compensation medium is horizontally positioned (FIG. 6) and the compensation medium is located vertically (FIG. 7) will be.

Figures 6a and 7a show all z components for the electric field distribution propagated along the positive x direction for the TE mode and Figures 6b and 7b show all z components for the electric field distribution propagated along the positive y direction for the TE mode, 6C and 7C show all z components for the magnetic field distribution propagated along the positive x direction for the TM mode and FIGS. 6D and 7D show the propagation along the positive y direction for the TM mode Lt; RTI ID = 0.0 &gt; z-component &lt; / RTI &gt;

As can be seen from FIGS. 6 and 7, it can be easily grasped how the electromagnetic field encounters the line segment when the normal material and the compensation medium are arranged horizontally or vertically.

However, it can be seen that a slight difference occurs in FIGS. 6 and 7, and in the case of FIG. 6, that is, in the case of a translucent device in which a normal material and a compensation medium have a transverse arrangement, Or incidence of the incident wave on a segment of the compensation medium, the incident wave is refracted or scattered in the object, whereas in the case of FIG. 7, that is, in the case of a translating apparatus in which the normal material and the compensation medium have a vertical arrangement, It can be seen that the behavior due to the normal material is compensated by the compensation medium when the line segment is incident.

As described above, it can be seen that the elliptical cylindrical transparentizing apparatus has excellent cloaking performance in all cases in which the compensation medium is arranged vertically.

8 shows the results of cloaking for an elliptical cylindrical transparency apparatus for making a quadrangular object placed in the interior transparent using a vertically arranged compensation medium, wherein both the permittivity and the transmittance of the quadrangular object (width 0.1 m, height 0.025 m) And the case where both the permittivity and the permeability of the compensation medium are -2.

As can be seen from the cloaking results shown in FIG. 8, even when the quadrangular object is disposed in the inner free space region, it can be seen that the cloaking performance is excellent in both the x and y directions with respect to the TE wave and the TM wave.

2) Bipolar cylindrical cloak with complementary media with compensation media

A two-dimensional elliptic cylindrical transparentizer is illuminated using both transverse electric (TE) (transverse electric) and polarized (TM) polarized plane waves with an operating frequency of 2 GHz (f = 2 GHz) and a wavelength of 15 cm

In this case, a finite-difference time-domain (FDTD) cell size of? X =? Y =? / 300 is used and a temporal discretization step is used to set the clamp stability, which is set to? T =? X / 2c ₀ (= 833.91 fsec) (Courant stability condition).

For the lossless transparency device mapped to the σ axis, the inner ellipse σ ₁ is set to 0.75π, the outer ellipse σ ₂ is set to 0.5π, the half-center distance (a) to 0.3m, and the compensation medium is set to σ ₁ and 2π-σ ₁ As shown in Fig.

The transparency apparatus according to the present invention, that is, the bipolar cylindrical transparency apparatus, is mapped to a line segment and its length is 0.6 m, which means that the inner space of the transparency apparatus shrinks to a line segment.

Electro-magnetic waves from the outside are applied as line segments. If the inner space is filled with a perfect conductor (PEC), it becomes a PEC line segment. If the inner space is filled with the compensating medium, it becomes a compensation line segment. For this reason, the clocking performance is very different. The PEC filled bipolar cylindrical translucent device showed good clocking performance only when the TM wave propagated along the positive x direction [JOSA B 30, 140-148 (2013)].

In contrast, in the present invention, it is important to compare the arrangement of the compensation medium with respect to the clocking performance of the transparent ring device mapped to the line segment in contrast to the single point mapped transparency device.

FIG. 9 shows the results of cloaking for the bipolar cylindrical transparentizing apparatus of the present invention mapped to the? -Axis.

Figure 9a shows all z components for the electric field distribution propagated along the positive x direction for the TE mode and Figure 9b shows all z components for the electric field distribution propagated along the positive y direction for the TE mode, Figure 9c shows all z components for the magnetic field distribution propagated along the positive x direction for the TM mode and Figure 9d shows all z components for the magnetic field distribution propagated along the positive y direction for the TM mode.

As can be seen from FIG. 9, it can be seen that the bipolar cylindrical vitrification apparatus in which the normal material and the compensation medium are arranged vertically shows the same good cloaking performance as the elliptic cylindrical vitrification apparatus shown in FIG.

FIG. 10 shows the result of cloaking for a bipolar cylindrical transparentizing apparatus in which a quadrangular object placed inside is made transparent by using a vertically arranged compensation medium. When the dielectric constant and transmittance of a quadrangular object (width 0.05 m, height 0.05 m) And the case where both the permittivity and the permeability of the compensation medium are -2.

As can be seen from the cloaking results shown in FIG. 10, even when the quadrangular object is disposed in the inner free space region, it can be seen that the cloaking performance is excellent in both the x and y directions with respect to the TE wave and the TM wave.

As described above, the transparentizing apparatus according to the present invention includes a meta material formed in a first region including an object to be hidden, and a compensation medium having a negative refractive index for compensating a positive refractive index in a free space inside the first region By arranging them symmetrically with respect to the region where the positive refractive index is formed, transparency can be improved and transparency performance can be improved for various types of polarized light such as TE wave and TM wave as well as incident wave.

Further, the present invention can be applied as a transparency method.

That is, in the transparency method according to the present invention, a transparency unit made of a first meta material is disposed so as to surround a first area for hiding a target object, and in a predetermined second area adjacent to the first area in the transparency unit, A compensation unit comprising a second metamaterial having a negative refractive index is disposed.

In this case, the transparency unit corresponds to the cloaking shell shown in FIG. 3, and the compensation unit may correspond to a region having a negative refractive index (-1, -1).

Further, the negative refractive index of the compensation medium constituting the compensation unit may be a negative refractive index for transparency to the object by compensating the positive refractive index of the first region, and the compensation unit may be a region that is symmetric with the region of the object .

Further, the compensation unit may be arranged to have the same size as the size of the object. Of course, the compensation unit may have a size corresponding to the positive refractive index area formed in the first area, and the area to be arranged may be a region symmetrical to the area where positive refractive index is formed.

The first meta material constituting the transparency unit may be designed so as to make the object transparent by distorting the space between the first area and the second area with respect to the electromagnetic wave. The first meta material may include a first area and a second area It can be designed by applying an analysis technique in which the change of the propagation path of the electromagnetic wave due to the distortion of space and time surrounding the wave is related to the refractive index of the electromagnetic wave.

The first meta-material may be designed by analyzing a Maxwell equation for a bipolar coordinate system representing a first region and a second region, and may be designed by interpreting Maxwell's equations for an elliptical coordinate system representing a first region and a second region It is possible.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- And various modifications and changes may be made thereto by those skilled in the art to which the present invention pertains.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (16)

A transparency apparatus for transparency of a target object within a predetermined first region using a meta-material,
A transparency unit surrounding the object in the first area and made of a first meta material; And
And a compensation unit which is disposed in a predetermined second region and is composed of a second metamaterial having a predetermined negative refractive index,
And the transparency unit is disposed so as to surround the first region and the second region. The method according to claim 1,
The negative refractive index,
Wherein the second region is a negative refractive index for compensating the positive refractive index of the first region to make the object transparent. The method according to claim 1,
The compensation unit comprising:
Wherein the transparent display device is disposed in an area symmetrical with the area of the object. The method of claim 3,
The compensation unit comprising:
Wherein the first region has a size equal to the size of the first region. The method according to claim 1,
The first meta-
Is designed to make the object transparent by distorting space-time surrounding the first area and the second area with respect to electromagnetic waves. 6. The method of claim 5,
The first meta-
Wherein the analyzing technique is designed to apply a change in the propagation path of the electromagnetic wave due to the distortion of the space between the first region and the second region to a refractive index for the electromagnetic wave. The method according to claim 1,
The first meta-
And the Maxwell's equations for the bipolar coordinate system representing the first region and the second region are analyzed. The method according to claim 1,
The first meta-
Wherein the first and second regions are designed by interpreting a Maxwell equation for an elliptical coordinate system representing the first region and the second region. A transparency method for transparency of a target object in a predetermined first region using a meta-material,
Disposing a transparency unit made of a first meta material so as to surround the object in the first area; And
Disposing a compensation unit comprising a second metamaterial having a predetermined negative refractive index in a second region predetermined to be adjacent to the first region in the transparency unit. 10. The method of claim 9,
The negative refractive index,
Wherein the first region is a negative refractive index for compensating for a positive refractive index of the first region and is transparent for the object. 10. The method of claim 9,
Wherein the step of arranging the compensation unit comprises:
Wherein the compensation unit is arranged in an area symmetrical to the area of the object. 12. The method of claim 11,
Wherein the step of arranging the compensation unit comprises:
Wherein the compensation unit has a size equal to the size of the first area. 10. The method of claim 9,
The first meta-
Wherein the object is designed to be transparent by distorting space-time surrounding the first region and the second region with respect to electromagnetic waves. 14. The method of claim 13,
The first meta-
Wherein the analysis is designed by applying an analysis technique in which the change of the traveling path of the electromagnetic wave due to the distortion of space-time surrounding the first area and the second area is made to correspond to the refractive index for the electromagnetic wave. 10. The method of claim 9,
The first meta-
Wherein the first and second regions are designed by interpreting a Maxwell equation for a bipolar coordinate system representing the first region and the second region. 10. The method of claim 9,
The first meta-
And expressing the Maxwell's equations for the elliptical coordinate system representing the first region and the second region.

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