KR20180065788A - Fabry-Perot wide angle resonator - Google Patents

Abstract

According to an aspect of the present invention, a Fabry-Perot wide angle resonator includes one or more negative refraction layers including a first reflection surface and a second reflection surface and exhibiting negative refraction between the first reflection surface and the second reflection surface; and one or more positive refraction layers exhibiting positive refraction between the first reflection surface and the second reflection surface. The Fabry-Perot wide angle resonator resonates at a wide incident angle range in a preset wavelength region. Accordingly, the present invention can operate regardless of an incident angle.

Description

Fabry-Perot wide angle resonator < RTI ID = 0.0 >

FIELD OF THE INVENTION The present invention relates to Fabry-Perot wide-angle resonators, and more particularly to Fabry-Perot wide-angle resonators having substantially the same resonance frequency for a wide angle of incidence or emission angle.

The Fabry-Perot resonance wavelength is a wavelength in which two mirrors are arranged so as to face each other with a certain distance therebetween, so that light is repeatedly reflected between the two mirrors, and when the length of the light path that reciprocates becomes an integral multiple of the wavelength of light, Is the wavelength that occurs.

In this case, each of the two mirrors may have a phase delay, and the phase delay of the light reflected repeatedly in the three-dimensional space may have a phase delay in a direction parallel to the mirror (longitudinal resonance mode) , As well as phase delays in both directions perpendicular to the direction of the mirror (vertical resonance mode, transverse resonance mode). In the Fabry-Perot resonator, since the different vertical resonance modes have different resonance wavelengths, the physical phenomena such as the improvement of the light absorption efficiency by the resonance and the improvement of the spontaneous emission efficiency appear at different wavelengths.

For example, in the mode where the intensity in the vertical direction is constant but the phase is delayed in proportion to the distance, in the case of the light absorbing device, it can be excited with the granular light inclined from the outside of the resonator with respect to the normal direction of the mirror, It is possible to excite tilted emission light. At this time, since the resonance wavelength differs depending on the angle of incidence, the performance of the device is deteriorated.

For example, when the viewing angle of an OLED-based display device is increased, the intensity of light is decreased or the color of light is different. A Fabry-Perot wide-angle resonator having almost the same resonance wavelength regardless of the incident angle or the emission angle, regardless of the vertical resonance mode, is required.

In order to solve the above-described problems, it is an object of the present invention to provide a Fabry-Perot wide-angle resonator that operates regardless of an incident angle.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a Fabry-Perot wide-angle resonator including a first reflector and a second reflector, A negative refraction layer; And at least one pair of refractive layers each showing both refraction between the first and second reflective surfaces, and resonates in a predetermined wavelength range in a wide incident angle range.

According to the present invention, since the Fabry-Perot wide-angle resonator in which a plurality of vertical direction modes have substantially the same resonance frequency in a specific parallel direction mode has almost no change in resonance frequency according to an incident angle or an emission angle, a solar cell, a light emitting diode ) Display, an organic light emitting diode (OLED) display, a laser, and the like, and can be used not only for electromagnetic waves other than visible light such as a microwave, but also for sound waves.

1 is a structural view of a Fabry-Perot wide-angle resonator according to the present invention;
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of forming a thin film using a photonic crystal.
FIG. 3 is an exemplary view for explaining a meta material having an indefinite effective permittivity tensor according to a partial embodiment of the present invention; FIG.
4 is an exemplary view for explaining a meta surface showing negative refraction according to a partial embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, the terms " comprises, " and / or "comprising" refer to the presence or absence of one or more other components, steps, operations, and / Or additions.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The Fabry-Perot resonance wavelength is a wavelength in which two mirrors are arranged so as to face each other with a certain distance therebetween, so that light is repeatedly reflected between the two mirrors, and when the length of the light path that reciprocates becomes an integral multiple of the wavelength of light, Is the wavelength that occurs.

The Fabry-Perot resonance condition can be explained by using the following equation.

In the case where a medium having a refractive index other than a vacuum is included in the resonator, the wavelength in the medium differs from the wavelength in the vacuum due to the refractive index of the medium, and thus the above equation is created using a wave number, not a wavelength, When this is an integer, the resonance condition becomes.

When one or both of the two mirrors used in the Fabry-Perot resonator have a reflectance of less than 100% and a transmittance of more than 0%, the light reaching the resonator from the outside is absorbed into the resonator Or the light generated inside the resonator may be emitted to the outside (a light emitting element such as an LED).

When the wavelength of light incident on the inside of the resonator is similar to the resonance wavelength, the light absorbing element absorbs more light due to the resonance phenomenon, thereby increasing the light absorbing efficiency.

When the emission wavelength of the light emitting device coincides with the resonant wavelength of the resonator, the spontaneous emission rate is increased due to the Purcell effect, so that the emission efficiency of light can be increased. If the amount of light is sufficient for the amount absorbed or emitted outside the resonator, the laser can be implemented by stimulated emission phenomenon.

Instead of using two mirrors as described above, the Fabry-Perot resonator can use a boundary surface of two mediums instead of a mirror, or use a grating structure or a photonic crystal structure. That is, the mirror can be seen as a boundary with a reflectance greater than 0% and less than 100%.

In particular, if one of the reflection surfaces (mirror) is a phase-delayed reflection surface whose phase is changed by 180 degrees and the other reflection surface (mirror) is a mirror whose phase does not change and when the reciprocation distance is a wavelength x (integer +0.5) Interference occurs. In general terms, when the phase delay of each reflective surface is Φ ₁ , Φ ₂ ,

The Fabry-Perot wide-angle resonator according to the present invention can have substantially the same resonance wavelength for a plurality of vertical resonance modes.

The Fabry-Perot wide-angle resonator according to the present invention realizes a wide-angle resonator using a medium having a normal medium and negative refraction. In this case, the medium having a negative refractive index and the medium having a negative refractive index are different concepts.

The Fabry-Perot wide-angle resonator according to the present invention includes both refraction layers and a negative refraction layer. According to the present invention, it has almost the same resonance wavelength for a plurality of vertical direction resonance modes. In other words, it has almost the same resonance wavelength for a wide range of incident angles or emission angles. The phase retardation in the normal medium with both refraction and the phase retardation in the medium with negative refraction should be opposite to each other and the partial reflection due to the impedance difference at the interface between the medium with both refraction and the medium with negative refraction The total reciprocal phase delay should be designed so that the resonance conditions are met at the same wavelength.

1 is a structural view of a Fabry-Perot wide-angle resonator according to the present invention.

The Fabry-Perot wide-angle resonator according to the present invention includes a first reflection surface, a second reflection surface, and a negative refraction layer both refraction layers.

The first reflection surface and the second reflection surface may be any of a mirror made of a conductive metallic material, a grating structure, a mirror made of a photonic crystal structure, and a mirror having a boundary surface between two media having different impedances, .

Wherein the first refraction surface and the second refraction layer are present between the first reflection surface and the second reflection surface, the first reflection surface is formed by a first medium adjacent to the toned refraction layer, The second reflective surface may be formed by a second medium adjacent to the second reflective surface.

The number of layers existing between the first reflection surface and the second reflection surface may be two or more.

1 (b) shows a Fabry-Perot wide-angle resonator laminated in the order of a second reflection surface, a negative refraction layer, a two refraction layer, a negative refraction layer and a first reflection surface, FIG. 1 (c) FIG. 1 (d) shows a Fabry-Perot wide-angle resonator laminated in the order of the first refraction layer, the second refraction layer, the negative refraction layer, the first refraction layer and the first refection surface, , A negative refraction layer, and a first reflective surface are shown in the Fabry-Perot wide-angle resonator. The above-described order of lamination and the number of laminated layers are illustrative and do not limit the scope of the invention.

Further, both of the refraction layers and the negative refraction layer may have a plurality of laminated structures. For example, both the refraction layers and the negative refraction layer may be structures in which different semiconductor materials having different band gaps are stacked. In particular, a negative refraction layer (layer exhibiting negative refraction) can be formed using a photonic crystal structure, a three-dimensional metamaterial, and a meta surface.

2 illustrates a reciprocal lattice space of a photonic crystal structure for explaining a method of forming a negative refraction layer using a photonic crystal according to a partial embodiment of the present invention.

A complex structure in which a three-dimensional structure is repeatedly formed at a half-wave period of a target wavelength is called a photonic crystal, in which a unique optical characteristic is exhibited by destructive interference and constructive interference of light scattered in each unit structure. In this photonic crystal structure, negative refraction occurs. There is a negative refraction phenomenon appearing in the vicinity of the specific band edge and a negative refraction phenomenon appearing in the vicinity of the band center (gamma point) in the upper band.

Figure 2 shows the Brillouin region in the reciprocal lattice space of the lattice structure. 2 (a), or in the vicinity of H in the body-centered cubic crystal, or in the vicinity of X in the center-cubic crystal, the modes of the first band and the second band are negative refraction Which is called a negative refraction phenomenon in the vicinity of the band edge.

In the above-described first and second bands, a negative refraction phenomenon appears at a point nearest to the gamma point. However, in the upper band (for example, the third band), negative refraction . In the cubic crystal, the body-centered cubic crystal, and the face-centered cubic crystal shown in Fig. 2, negative refraction occurs in the vicinity of the gamma point of the third band.

When a three-dimensional structure is repeated cyclically or non-periodically at intervals of a level smaller than half wavelength of a specific wavelength and each unit structure has a resonance phenomenon at a specific wavelength, a complex medium in which unique optical characteristics appear near the resonance wavelength or at other wavelengths Is called a metamaterial, and a negative refraction layer can be formed using a meta material.

Specifically, a negative refraction layer can be formed using an indefinite code meta material whose sign of permittivity or permeability changes according to the direction of an electromagnetic field, and a double negative metamaterial having a negative permittivity and a negative permeability, Can be formed.

3 is an exemplary view for explaining a meta-material having an indefinite effective permittivity tensor according to an embodiment of the present invention.

The effective dielectric of a meta-material is generally a two-dimensional tensor, which when expressed as a matrix, is an indefinite-coded matrix.

3 (a)), a thin film (Fig. 3 (b)) and an elliptical revolution body (Fig. 3 (c)) are portions of a conductor whose negative real part is a dielectric constant, ≪ / RTI > where the real part of < RTI ID = 0.0 > When the absolute value of the dielectric constant real part of the conductor material is much larger than the absolute value of the dielectric constant real part of the dielectric material, the conductor wire shape of Fig. 3A shows a negative dielectric constant with respect to the electric field in the direction parallel to the wire, The effective permittivity may be a positive value for an electric field on a plane perpendicular to the plane. If the wires are arranged perpendicular to the mirror surface, negative refraction occurs.

If the absolute value of the dielectric constant real part of the conductor material does not have a value significantly larger than the absolute value of the dielectric constant real part of the dielectric material, the effective dielectric constant according to the direction differs depending on the volume ratio of the conductor material and the dielectric material and the shape of the conductor material . In particular, the effective dielectric constant is positive for an electric field in a direction parallel to the wire, and the effective permittivity for a planar electric field perpendicular to the wire can be negative. As described above, when the absolute value of the dielectric constant real part of the conductor material is small, a thin film (FIG. 3 (b)) laminated in parallel to the reflective surface may be used instead of the wire to cause negative refraction in a desired direction have.

3 (c) shows an elliptical rotating body arranged in a direction perpendicular to the reflection surface instead of the wire and the thin film. However, this may be an elliptical column, a square column, or a hexagonal column.

In the structure of FIG. 3 (c), the real part of the dielectric constant may be negative at a wavelength shorter than the resonance wavelength in the vertical direction of the reflecting surface depending on the length of the conductor, so that a negative refraction phenomenon may occur.

Using a meta material of a mesh structure can produce a medium in which the real part of the effective permeability in the visible light region is negative and the real part of the permittivity is also negative. As described above, negative refraction phenomenon may occur using a double negative metamaterial in which the real part of permeability and permittivity are both negative. The double negative material may be formed using a structure other than the mesh structure.

A structure having a height smaller than a specific wavelength repeats periodically or non-periodically at intervals of a level smaller than a half wavelength of the specific wavelength in a plane, and a resonance phenomenon occurs due to the shape of the structure and the repetitive period, A composite surface with unique optical properties at or near the wavelength is called a metasurface. The negative refraction phenomenon can be realized by using the meta surface.

Since the meta surface has a surface structure having a height level lower than the wavelength, it is difficult to observe the light path due to the thin thickness, and it is difficult to easily observe the ordinary 'refractive index'. We define it strictly as follows.

Consider a situation where an incident wave that reaches the meta surface in the direction of the incident angle? (0?? <90 占 from the normal direction of the surface passes through the surface of the surface and becomes a transmission wave. In the case of a meta surface in which unit structures smaller than half wavelength are uniformly arranged, if the incident wave is a uniform plane wave, the transmitted wave becomes a uniform plane wave.

4 is an exemplary view for explaining a meta surface showing negative refraction according to a partial embodiment of the present invention.

Among the points on the meta surface, there are a point A located on the incident wave side and a point B separated from the point A by the thickness of the meta surface in the direction perpendicular to the surface. A value obtained by subtracting the phase of the incident wave of the point A from the phase of the transmission wave of the point B is referred to as "phase delay at the meta surface ", and when the phase delay is decreased as the incident angle increases with respect to the phase delay, And when the phase delay increases as the incident angle increases, it is called a negative refraction meta surface.

Resonance conditions of the Fabry-Perot wide-angle resonator in which N layers including at least one of a negative refraction layer and a refraction layer are inserted in the first reflection surface and the second reflection surface are as follows.

는 p층에서의 파수를 의미하고,

는 p층의 높이를 의미한다. N은 전체 층의 수이다.

Means the number of waves in the p-layer,

Is the height of the p-layer. N is the total number of layers.

가 변화하고, 이는 음굴절 층 또는 양굴절 층의 광학 특성에 의하여 결정되는 것이므로, 입사각 에 따른

와 높이

를 층별로 조절함으로써, 입사각 θ에 무관하게

값이 일정하게 되도록 패브리-페로 광각 공진기를 설계할 수 있다.As described above, according to the incident angle &amp;thetas;

Which is determined by the optical characteristics of the negative refraction layer or both refraction layers,

And height

, It is possible to control the angle of incidence θ

The Fabry-Perot wide-angle resonator can be designed to have a constant value.

의 값이 다양하게 나타날 수 있으므로, 음굴절 층 또는 양굴절 층의 구조 선택과 두께 선택은 간단히 구할 수는 없고, 전달 행렬법(transfer matrix method) 또는 유한 차분 시간 영역 방법(finite difference time-domain Method)에 의하여 적절한 구조를 선택할 수 있다.In the Fabry-Perot wide-angle resonator according to the present invention, there is actually a reflection at the interface of each layer,

The structure selection and the thickness selection of the negative refraction layer or the both refraction layers can not be simply obtained, and the transfer matrix method or the finite difference time-domain method ) Can select an appropriate structure.

While the present invention has been described in detail with reference to the accompanying drawings, it is to be understood that the invention is not limited to the above-described embodiments. Those skilled in the art will appreciate that various modifications, Of course, this is possible. Accordingly, the scope of protection of the present invention should not be limited to the above-described embodiments, but should be determined by the description of the following claims.

Claims (8)

A Fabry-Perot wide-angle resonator comprising a first reflector and a second reflector,
At least one negative refraction layer exhibiting negative refraction between the first reflective surface and the second reflective surface; And
One or more both refractive layers having both reflections between the first reflective surface and the second reflective surface;
Containing
Fabry-Perot wide-angle resonator resonates in a wide range of incident angles over a wide range of wavelengths.
The method according to claim 1,
Wherein the first reflecting surface and the second reflecting surface are formed by a first reflecting surface,
A reflecting surface made of a grating structure or a photonic crystal structure
Fabry-Perot wide-angle resonator.
The method according to claim 1,
A first reflective layer present on the first reflective surface; And
A second reflective layer present below the second reflective surface;
Further comprising:
Wherein the first reflective layer comprises:
And having a different impedance from a layer existing immediately below the first reflection surface,
Wherein the second reflective layer
The second reflecting surface having a different impedance from the layer existing directly on the second reflecting surface,
The first reflecting surface may be formed,
Wherein the first reflection layer is a boundary surface between the first reflection layer and a layer immediately below the first reflection surface,
The second reflecting surface may be formed,
And the second reflective layer is an interface between the second reflective layer and a layer existing directly on the second reflective surface.
Fabry-Perot wide-angle resonator.
The method according to claim 1,
Wherein the negative refraction layer
A photonic crystal structure of a three-dimensional structure,
Wherein the photonic crystal structure comprises:
A crystal formed repeatedly at a period of a half wavelength level of a specific wavelength is regarded as a unit structure,
The unit structure includes:
A cubic crystal structure, a body-centered cubic crystal structure, and a face-centered cubic crystal structure.
Fabry-Perot wide-angle resonator.
The method according to claim 1,
Wherein the negative refraction layer
A wire made of a conductor material arranged in a direction perpendicular to the second reflection surface, and a negative refraction layer portion excluding the wire are three-dimensional metamaterials filled with a dielectric material having a positive real part of dielectric constant,
The real part of the dielectric constant of the conductor material is negative,
The absolute value of the real part of the conductor material is greater than the absolute value of the real part of the dielectric constant of the dielectric.
Fabry-Perot wide-angle resonator.
The method according to claim 1,
Wherein the negative refraction layer
A thin film made of a conductor material arranged in a direction parallel to the second reflection surface and a negative refraction layer portion excluding the thin film are three dimensional metamaterials filled with a dielectric material whose real part of dielectric constant is positive,
The real part of the dielectric constant of the conductor material is negative,
The absolute value of the real part of the conductor material is smaller than the absolute value of the real part of the dielectric constant of the dielectric material.
Fabry-Perot wide-angle resonator.
The method according to claim 1,
Wherein the negative refraction layer
A plurality of wires made of a conductor material arranged in a direction perpendicular to the second reflection surface and a negative refraction layer portion excluding the wire are three dimensional metamaterials filled with a dielectric material having a positive real part of dielectric constant,
The real part of the dielectric constant of the conductor material is negative,
The wire
In the negative refraction layer, two or more linearly arranged in the vertical direction of the second reflection surface, and the length is shorter than the resonance wavelength,
The absolute value of the real part of the conductor material is greater than the absolute value of the real part of the dielectric constant of the dielectric.
Fabry-Perot wide-angle resonator.
The method according to claim 1,
The number of the negative refraction layers is one,
The two refraction layers are one,
The product of the wave number and the height with respect to the incident angle &amp;thetas; of each layer is calculated
And the height of each layer is determined such that the sum of the calculated products is constant.
Fabry-Perot wide-angle resonator.

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