KR20170013802A - Plsmonic device - Google Patents

Abstract

The present invention relates to a plasmonic device. More specifically, the present invention relates to a plasmonic device which improves a passive device generating a mode change in a waveguide.

Description

[0001] PLASMONIC DEVICE [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasmonic element, and more particularly, to a plasmonic element in which a passive element for causing a mode change in a waveguide is improved.

Plasmon is a collective excitation corresponding to the oscillation of free electron density in the metal. The electron density interacts with the electromagnetic field, so that the photon and plasmon can combine. The coupled surface mode in which the plasmon and photons on the metal surface are combined is called surface plasmon polariton. These surface modes allow the light to be focused above the diffraction limit, which is considered to be highly applicable in optical storage media, optical integrated circuits, and nonlinear optical research.

One of the simplest plasmonic elements is a waveguide that is the path through which the SPP propagates. Propagation characteristics such as dispersion relation and propagation length vary depending on the shape and size of the waveguide, and it is also possible to control these characteristics through waveguide design. A waveguide can have several propagation modes, and each mode operates as an independent propagation channel, and multiplexing using the modes is also possible unless there is a structure for combining the modes.

There may be times when it is necessary to move the SPP of one channel to another channel by interacting with independently operating radio modes as needed. For example, at a specific location, the SPP proceeds at a slow rate and must interact with the substance for a long time It is difficult to send the SPP from the position where the SPP is generated to the corresponding position because the energy loss is excessively large when only the slow SPP propagation channel is used from the beginning. In such a case, it would be much more efficient to move the loss to the nearest destination through the small SPP channel and convert it to a slower SPP through the mode converter.

To create inter-mode interaction, a waveguide section deformation is required to break the symmetry in the SPP propagation direction.

In general, if the waveguide cross-section is not constant, each propagation mode is no longer independent, resulting in transition to multiple transmission and reflection modes. Thus, a very simple localized deformation can be used to create inter-mode interaction. However, structures with too low complexity generally have limited efficiency, and in most cases it is impossible to avoid the transmission and reflection of unintended modes. It is also possible to cause selective mode conversion through sophisticated design, such as a method using an adiabatic waveguide section change, a mode transition phenomenon by a lattice, and a shape optimization. In the case of the design using the adiabatic waveguide section change or grating, only the weak and slow change which can be considered as the perturbation is made, and therefore, only the desired reflection of the desired mode can be mainly caused by the phase matching condition. However, in order to enable such a design, a long length is required to be unsuitable as a nano device, which is a great disadvantage in practical use. The design using shape optimization can be very efficient in terms of the conversion efficiency while maintaining a proper device size, but since the optimized shape is generally very complicated, it requires a highly precise process such as an electron beam process, which lowers the productivity. Therefore, it is necessary to design a device which is simple in size but small in size and capable of selective mode conversion.

Published Patent Application No. 1997-0019144

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a plasmonic device in which a passive element for causing a mode change in a waveguide is improved.

In order to achieve the above object, a plasmonic device according to the present invention is a plasmonic device for converting and transmitting an opposite-SPP mode to a symmetric SPP mode, comprising: a body made of a metal material having a predetermined permittivity; A central waveguide extending in one direction through the inside of the body and propagating SPP; A first filter formed on the central waveguide; Converter; And a second filter, wherein the central waveguide is composed of a first dielectric having a predetermined first permittivity value such that the SPP propagates, and wherein the converter is located between the first filter and the second filter, 1 filter intercepts the transmission of the symmetric SPP mode and passes the antisense SPP mode, the second filter interrupts the transmission of the antisense SPP mode and passes the symmetric SPP mode, Mode.

Preferably, the first filter is composed of a vertical waveguide having a predetermined length in a direction perpendicular to the extending direction of the central waveguide and a predetermined width in the extending direction of the central waveguide, And extend symmetrically with respect to the direction of extension of both sides.

Preferably, the converter is formed of a groove having a predetermined depth in the one-sided vertical direction with respect to the extending direction of the central waveguide and having a predetermined width in the extending direction of the central waveguide.

Preferably, the second filter is composed of a second dielectric material which is located in the central waveguide and has a predetermined thickness in the extending direction of the central waveguide and has a second dielectric constant value, And has a smaller value than the permittivity value.

Preferably, the first filter and the converter are spaced apart from each other with a first gap, and the converter and the second filter are spaced apart with a second gap.

Preferably, the magnitudes of the first spacing and the second spacing are such that the reflection coefficient of the opposite-SPP mode across the plasmonic element to which the opposite-SPP mode will propagate from the first filter to the second filter 0 < / RTI >

A method of manufacturing a plasmonic device according to an embodiment of the present invention includes: a body made of a metal material having a predetermined dielectric constant; A central waveguide extending in one direction through the inside of the body and propagating SPP; A first filter formed on the central waveguide; Converter; And a second filter, wherein the central waveguide is composed of a first dielectric having a predetermined first permittivity value such that the SPP propagates, and wherein the converter is located between the first filter and the second filter, 1 converter and the converter are spaced apart from each other with a first distance, the converter and the second filter are spaced apart from each other with a second distance, and the first filter is arranged in a direction perpendicular to the extending direction of the center waveguide And a vertical waveguide having a predetermined length and a predetermined width in the extending direction of the central waveguide, wherein the vertical waveguide extends symmetrically with respect to the extending direction of the central waveguide in both vertical directions so that the transmission in the symmetric SPP mode And the second filter has a second permittivity value smaller than the first permittivity and has a second permittivity value smaller than the first permittivity value in the extending direction of the center waveguide Wherein said converter has a predetermined thickness and is formed of a second dielectric so as to cut off the transmission of the opposite SPP mode and pass the symmetric SPP mode, said converter having a predetermined depth in one vertical direction with respect to the extending direction of said central waveguide, And converting the opposite SPP mode into a symmetric SPP mode and converting the opposite SPP mode into a symmetric SPP mode, the method comprising the steps of:

(a) determining a length and a width of a vertical waveguide constituting the first filter;

(b) determining a thickness of the second filter;

(c) determining the width and depth of the converter;

(d) determining a value of the interval 1 satisfying Equation (1);

(Equation 1

: 제1 필터와 컨버터를 묶은 블록의 반대칭 SPP 모드에 대한 좌측 반사계수,

: The left reflection coefficient for the antiphase SPP mode of the block binding the first filter and the converter,

: 제1 필터와 컨버터를 묶은 블록의 반대칭 SPP 모드에 대한 우측 반사계수

: Antilogarithm of the block binding the first filter and converter The right reflection coefficient for the SPP mode

: 제1 필터와 컨버터를 묶은 블록의 반대칭 SPP 모드에 대한 투과계수)

: Transmission coefficient for counter-tangent SPP mode of the first filter and converter-bound block)

 (e) substituting the value of the interval 1 determined in the step (d) into the following equation 2, and determining the value of the interval 2 so that R becomes zero.

 (2)

: 제2 필터에 의해 반사된 반대칭 SPP 모드가 겪는 위상변화

: The phase shift experienced by the anti-SPP mode reflected by the second filter

: 반대칭 SPP 모드의 전파상수

: Electromagnetic wave in SPP mode

: 제2 간격의 크기

: The size of the second gap

Preferably, the step (a)

The transmission amount of the symmetric SPP mode is minimized by simulating that the transmission amount of the symmetric SPP mode is changed by varying the width and length of the vertical waveguide to select the region where the transmission amount of the opposite SPP mode is secured.

Preferably, the step (b) further includes a step of adjusting the permeation amount of the symmetric SPP mode to a maximum value according to the pattern of the transmission amount of the symmetric SPP mode with respect to the second filter exhibiting a vibrational pattern by Fabry-Perot resonance, 2 filter thickness is selected as the thickness of the second filter, and the thickness of the second filter is selected as the minimum thickness value of the thickness values exceeding the critical thickness at which the opposite SPP mode is cut off.

Preferably, the step (c) further comprises the step of simulating the transmittance of the symmetric SPP mode with respect to the incident opposing SPP mode by varying the width and depth of the converter and selecting the width and depth of the converter according to the conversion efficiency do.

Preferably, in the step (d), the transmission and reflection coefficients for the block in which the first filter and the converter are bundled are changed while changing the interval 1, and the left side and the right side of Equation 1 are compared, 1 is selected. Through this process, the reflection of the opposite-SPP mode can be eliminated through the step (e) only when Equation 1 is satisfied.

Preferably, in the step (e), the interval 2 is selected such that the reflectivity R of the opposite SPP mode for the entire structure is 0, changing the interval 2.

In the plasmonic device having the structure proposed in the present invention, only one output mode is emitted for the input mode. This can reduce the need for various filters or optical isolators needed to eliminate incidental noise, thus simplifying optical system design. In addition, since the structure according to the present invention is composed of only a combination of parts having an extremely simple shape, there is an advantage that the shape is much simpler than the shape optimization technique. Finally, since the mode conversion device is a resonance structure as a whole, the overall length can be very short, which is advantageous for miniaturization.

1 is a conceptual diagram showing the entire structure of a plasmonic device according to the present invention.
FIG. 2 is a view showing the transmission amounts of the symmetric and anti-symmetric SPP modes according to the width and length of the vertical waveguide constituting the first filter.
Fig. 3 is a diagram showing the transmission amount of the opposite-SPP mode depending on the thickness of the second filter.
4 is a view showing the transmission amount of the symmetric SPP mode according to the thickness of the second filter, respectively.
5 is a graph showing the transmittance of the symmetric SPP mode according to the depth and width of the converter.
6 is a diagram showing a structure of a plasmonic element.
7 is a diagram showing changes in the left side and the right side of Equation 2 as the interval 1 is changed.
8 is a diagram showing a variation of the reflectance in the opposite-SPP mode of the plasmon element by determining the interval 1 and changing the interval 2. Fig.
9 is a diagram showing a magnetic field intensity distribution of a plasmonic element.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present embodiments are not intended to be limiting.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

 Hereinafter, a method of manufacturing the plasmonic element 1, which is optimally designed together with the structure of the plasmonic element 1 according to an embodiment of the present invention will be described. The plasma optical element 1 according to the present invention includes a body 100, a central waveguide 200 passing through the body 100, a first filter 300 formed on the central waveguide 200, (400), and a second filter (500).

The body 100 is entirely made of a metal material and has a predetermined length and width. Hereinafter, with reference to FIG. 1, the horizontal direction in FIG. 1 will be referred to as a longitudinal direction, and the vertical direction will be described as a width direction. Meanwhile, preferably, the body 100 may be made of a silver (Ag) material.

The central waveguide 200 extends in the longitudinal direction of the body 100 through the inside of the body 100 and has a predetermined width. The central waveguide 200 is composed of a dielectric having a predetermined first permittivity value so that the SPP propagates. Preferably, according to one embodiment, the dielectric constituting the central waveguide 200 may be composed of silicon (? = 12.15) and its width may be 200 nm.

The SPP is propagated through the central waveguide 200. In Fig. 1, A on the left indicates propagation of the opposite SPP, and B on the right indicates propagation of the symmetric SPP.

The first filter 300 is formed on the central waveguide 200. The first filter 300 prevents the symmetric SPP mode from being transmitted first, and secondly, it is optimally designed to maximize the transmission of the opposite SPP mode. This is designed to block reflections in the symmetric SPP mode and increase the probability that the opposite-order SPP mode will be canceled by the destructive interference.

Preferably, the first filter 300 may be designed as a notch filter consisting of two vertical waveguides protruding on both sides in the width direction of the central waveguide 200. That is, the first filter 300 may include a first vertical waveguide 310 and a second vertical waveguide 320 formed on both sides of the central waveguide 200. Each vertical waveguide has a predetermined length in the width direction of the body 100 and a predetermined width in the longitudinal direction of the body 100.

The optimized design of the first filter 300 utilizes the fact that the transmission amount varies depending on the width and length of the vertical waveguide perpendicular to the central waveguide 200. This design simulates the variation of the transmission amount of the symmetric and anti-symmetric SPP modes by changing the width and length of the vertical waveguide, thereby satisfying the condition that the transmission amount of the symmetric SPP mode is minimized and the transmission amount of the opposite- And the area to be selected is selected.

For example, in FIG. 2, the transmission of the symmetric SPP mode is less than 3% and the transmission of the opposite SPP mode is 70% at a width of 240 nm and a length of 330 nm.

Then, the second filter 500 is designed to block the transmission of the opposite-SPP mode and pass the symmetric SPP mode. Preferably, it is desirable to completely block the transmission of the counter-SPP mode and to completely pass the symmetric SPP mode. Thus, the transmission of the opposite SPP mode is blocked and the design is simplified.

The second filter 500 is formed by replacing one section of the central waveguide 200 composed of the first dielectric material with a second dielectric material having a different permittivity from that of the other part so that the counterpart SPP mode has a cutoff below a certain frequency, . The higher the dielectric constant of the second dielectric constituting the second filter 500 is, the lower the frequency at which the cutoff frequency is lowered. Thus, if the dielectric constant of the second dielectric is lowered, the opposite-symmetric SPP mode can be eliminated.

Accordingly, the second filter 500 acts as a barrier for the opposite SPP mode. As shown in FIG. 3, it can be seen that the transmittance of the opposite SPP mode decreases with a tendency similar to the tunneling phenomenon depending on the thickness of the barrier. The thickness of the second filter 500 required to prevent transmission of the antisense SPP mode is approximately 150 nm or more. This is called the critical thickness for convenience.

4, the relationship between the transmittance of the symmetric SPP mode and the thickness of the second filter 500 shows a vibration pattern due to Fabry-Perot resonance. 4, almost complete transmission occurs when the thickness of the second filter 500 is a multiple of 470 nm.

When the thickness is equal to or greater than the critical thickness, and the thickness is a multiple of 470 nm, the second filter 500 blocks transmission of the opposite SPP mode and completely transmits the symmetric SPP mode. It is desirable that the second filter 500 has a minimum thickness, so that it is preferable that the thickness of the second filter 500 is 470 nm.

The converter 400 is then designed to have the highest conversion efficiency between the symmetric SPP mode and the opposite SPP mode with a single structure reference without a resonant structure. Since the second filter 500 is designed to completely transmit the symmetric SPP mode, a high conversion efficiency of the converter 400 itself can further contribute to the efficiency of the entire mode conversion.

The converter 400 includes a rectangular groove formed on one side in the width direction of the central waveguide 200 and has a predetermined width in the longitudinal direction of the body 100 and a predetermined depth in the width direction of the body 100 .

Concrete design of the converter 400 may be done in a manner similar to the design of the first filter 300. That is, it is simulated how the transmittance of the symmetric SPP mode appears when the opposite-pitch SPP mode is entered and the width and depth of the converter 400 are adjusted, respectively. For example, as shown in FIG. 5, it can be seen that the efficiency is optimized to 43% when the width is 200 nm and the depth is 70 nm.

Next, the size of the first gap M between the first filter 300 and the converter 400 is determined, and the size of the second gap N between the converter 400 and the second filter 500 . By determining the magnitude of the first spacing M and the second spacing N, the reflection of the opposite SPP mode in the structure of the entire plasmonic element 1 is removed.

First, the first interval M is obtained by using a condition that indicates whether reflection of the opposite-SPP mode can be removed by adjusting the second interval N. [ This condition can be obtained by the following equation (1) which indicates the complex reflection coefficient of the entire plasmonic element (1).

(식 1)

(Equation 1)

은 본 발명에 따른 플라즈모닉 소자(1) 전체의 반대칭 SPP 모드의 반사계수이며

,

,

는 각각 제1 필터(300)와 컨버터(400)를 묶은 블록의 반대칭 SPP 모드에 대한 좌측 반사계수, 우측 반사계수와 투과계수이다. 즉, 도 6 을 참조하면, 제1 필터(300)와 컨버터(400)를 묶은 블록을 K 라고 할 때, 대칭 SPP 모드가 좌측에서 입사할 때, 좌측으로 도로 반사되는 것을 나타내는 좌측 반사계수가

, 우측에서 반사되어 도로 입사하는 대칭 SPP 모드를 우측으로 다시 반사시키는 것을 나타내는 우측 반사계수가

, 대칭 SPP 모드가 투과하는 것을 나타내는 투과계수가

이다.From here

Is the reflection coefficient of the opposite SPP mode of the entire plasmonic device 1 according to the present invention

,

,

Are the left reflection coefficient, the right reflection coefficient, and the transmission coefficient for the opposite SPP mode of the block in which the first filter 300 and the converter 400 are bundled, respectively. 6, when the block connecting the first filter 300 and the converter 400 is K, when the symmetric SPP mode is incident on the left side, the left reflection coefficient indicating that the reflection is reflected to the left side

, The right reflection coefficient indicating that the symmetric SPP mode reflected from the right side and incident on the road is reflected back to the right side

, A transmission coefficient indicating that the symmetric SPP mode is transmitted

to be.

는 제2 필터(500)에 의해 반사된 반대칭 SPP 모드가 겪는 위상변화를 나타내고

는 반대칭 SPP 모드의 전파상수이며,

는 제2 간격(N)의 크기를 나타낸다. 반사 및 투과계수인

,

,

는 제1 간격(M)의 크기에 의존한다. together,

Represents the phase change experienced by the opposing SPP mode reflected by the second filter 500

Is the propagation constant of the opposite SPP mode,

Represents the size of the second gap N. Reflection and transmission coefficient

,

,

Depends on the size of the first spacing M.

The application of Equation 1 is independent of the design of the converter 400 and the first filter 300. Equation 1 can be ignored if energy loss is negligible and the reflection of the symmetric SPP mode in the second filter 500 is negligible. Since the energy loss is not preferable, the first dielectric and the second dielectric use a material which hardly absorbs light, and the waveguide width is also narrowed as necessary to reduce the loss as much as possible, so that Equation 1 can be applied.

의 변화에 의해

이 0을 만족시킬 조건은 아래의 식 2 와 같이 주어진다.Subsequently, the size of the second gap N

By the change of

The condition to satisfy this 0 is given by Equation 2 below.

(식 2)

(Equation 2)

Equation (2) can be derived from Equation (1) if the energy loss is not large in the process of the anti-nominal SPP mode transition being sufficiently small in the central waveguide (200) and the anti-symmetric SPP mode being reflected in the second filter (500).

의 허수부가 실수부보다 훨씬 작다는 것을 의미한다. 아울러, 반대칭 SPP 모드가 제2 필터(500)에서 반사되는 과정에서 에너지 손실이 작은 것은 반사율

의 크기가 1 에 가깝다는 것이므로, 반사율

의 절대값은 1 로 간주할 수 있다.The fact that the transverse loss of the opposing SPP is small is expressed mathematically as

Of the imaginary part is much smaller than the real part. In addition, when the SPP mode is reflected by the second filter 500,

Is close to 1, the reflectance

Can be regarded as 1.

가 입사된 광의 수 파장 정도의 크기를 갖는다는 전제 하에,

의 절대값은 1 에 가깝게 된다. 일 실시예에서는 광통신 대역인 1550 nm 의 광이 사용되었고, 이는 제2 간격(N)의 크기

가 상기 입사된 광의 수 파장 정도의 크기를 가지므로,

로 간주할 수 있다.Further, the size of the second gap N

Lt; RTI ID = 0.0 > wavelength < / RTI > of incident light,

Is close to 1. In one embodiment, light of 1550 nm, which is the optical communication band, is used, which is the size of the second interval N

Is about the number of wavelengths of the incident light,

.

Under the above premise, the process of obtaining Equation 2 will be described below.

를

로 하면, 아래와 같은 식 3 이 도출된다.In Equation 1,

To

, The following Equation 3 is derived.

(식 3)

(Equation 3)

을 복소평면에서 복소평면으로의 함수로 생각하면, 단위원

는 (식3)의 변환에 의해서 복소평면 상의 원으로 보내진다.

Is considered as a function from the complex plane to the complex plane,

Is sent to the circle on the complex plane by the transformation of (Equation 3).

More specifically, if the expression for any complex plane has the form of the following expression (4) and the absolute value of the variable satisfies the following expression (5), the expression (4) The function value appears in the form of a circle on the complex plane. At this time, the radius of the circle and the position of the center point are expressed by the following equations (6) and (7). That is, the function value appears as a circle on the complex plane, and the radius of the circle and the position of the center point can be derived through the respective coefficients of the equation.

(식 4)

(Equation 4)

(식 5)

(Equation 5)

(식 6)radius :

(Equation 6)

(식 7)Center point:

(Equation 7)

일 경우, 상기 원은 단지 중심점의 위치만

만큼 이동하게 된다.On the other hand,

, The circle is only the position of the center point

.

를

로 하여, 식 3이 도출되었으며, 이는 상기 식 4 와 그 형태가 같다. As described above, in Equation 1,

To

, And Equation 3 is derived, which is the same as Equation 4 above.

이므로, 상기 식 4 및 식 5 의 형태와 조건을 만족하게 된다.Also,

Therefore, the form and condition of the equations (4) and (5) are satisfied.

는 복소평면 상의 원의 궤적을 갖게 된다.Accordingly,

Has a locus of a circle on the complex plane.

가 나타내는 원의 반지름과 중심점의 위치를 구할 수 있다. On the other hand, if the terms of the equations (4), (6), and (7)

The radius of the circle and the position of the center point can be obtained.

First, the correspondence between Equation 4 and Equation 3 is as follows.

Accordingly, the radius of the circle and the position of the center point on the complex plane of the trajectory of Equation 3 are as follows.

(식 8)radius :

(Expression 8)

(식 9)Center point:

(Equation 9)

값은

를 변화시킴에 따라서 상기 반지름

을 갖고 중심점의 위치가

인 원의 궤적 상에서 이동한다. Accordingly,

The value is

The radius < RTI ID = 0.0 >

And the position of the center point is

And moves on the trajectory of the phosphorus circle.

는 제2 간격(N)의 크기

에 의존하므로, 결국 제2 간격(N)의 크기

를 변화시킴에 따라서

의 값이 상기 원의 궤적 상에서 변화하게 된다.here,

The size of the second gap N

The size of the second interval N

According to

Is changed on the locus of the circle.

의 값이 0 이기 위해서는 상기 원의 궤적이 원점을 지나야 한다. 즉, 원점에서 중심점 사이의 거리가 반지름과 같아서 상기 원의 궤적이 원점을 통과해야 한다. 이에 따라서, 반지름의 크기를 나타내는 식 8 과, 원점과 중심점 사이의 거리를 나타내는 식 9 가 같아야 하는 바, 이에 따라서 상기 식 8 과 식 9 를 등호로 엮으면 상기 식 2 가 도출된다.here,

The trajectory of the circle must pass through the origin. That is, the distance between the origin and the center point is equal to the radius, and the locus of the circle must pass through the origin. Accordingly, Equation (8) representing the magnitude of the radius and Equation (9) representing the distance between the origin and the center point should be the same. Accordingly, Equation (8) and Equation (9)

,

,

는 필터 1 과 컨버터(400)를 묶은 블록의 반대칭 SPP 모드에 대한 좌우 반사계수와 투과계수를 나타내는 바, 제1 간격(M)이 변화함에 따라서 변화한다. 이에 따른 좌변과 우변의 값을 그래프로 나타내면 도 7 와 같으며, 좌변의 값과 우변의 값이 일치하는 지점이 각각 원으로 표시되었다. 즉, 좌변의 값을 나타낸 그래프와 우변의 값을 나타낸 그래프가 서로 만나는 지점이 표시되었다.Next, the values of the left side and the right side of the equation (2) are graphically expressed by changing the size of the first interval (M), and the first interval (M) when the values of the left side and the right side are equal is found. That is, the size of the first interval M is changed, and the size of the first interval M satisfying the expression 2 is searched. As described above,

,

,

Right reflection coefficient and transmission coefficient for the opposite SPP mode of the block in which the filter 1 and the converter 400 are bundled, and changes as the first interval M changes. The values of the left and right sides according to the results are shown in FIG. 7, and the points where the value of the left side and the value of the right side coincide with each other are indicated by circles. That is, the point where the graph showing the value of the left side and the graph showing the value of the right side meet are displayed.

,

,

를 결정하고, 이어서 제2 간격(N)의 크기 가 변화함에 따른

의 값을 구한다. Then, according to the value of the first interval M derived according to the above procedure,

,

,

, And then determines the size of the second gap N Due to changes in

.

의 크기가 0 이 되도록 할 수 있음을 알 수 있다. 즉, 제1 간격(M)의 크기가 상기 식 2 를 만족하는 120 nm 일 때, 제2 간격(N)의 크기의 변화에 따라서

는 0 을 지나고 있다. 반면에, 제1 간격(M)의 크기가 상기 식 2 를 만족하지 않는 180 nm 또는 300 nm 인 경우에는, 제2 간격(N)을 아무리 변화시켜도

의 값은 0 을 지나지 않고 있다. 8, the size of the second interval N is adjusted only in the case of the size of the first interval M that satisfies the condition of Equation 2,

Can be made to be zero. That is, when the size of the first interval M is 120 nm satisfying the above-mentioned formula 2, according to the change of the size of the second interval N

0 < / RTI > On the other hand, in the case where the size of the first interval M is 180 nm or 300 nm which does not satisfy the formula 2, no matter how the second interval N is changed

The value of " 0 "

In conclusion, after finding the size of the first interval M satisfying the expression 2, the first interval M is substituted into the expression 1, and the complex reflection coefficient of the SPP mode of the opposite structure of the entire structure of the plasma- The reflection of the opposite-pitch SPP mode is removed from the structure of the entire plasmonic device 1 by finding the size of the second interval N at which the value of the second interval N becomes zero.

According to the embodiment, the size of the first interval M is 120 nm, the size of the second interval N is 320 nm, the final conversion efficiency is 47%, and all components other than the transmission through the symmetric SPP mode It is possible to design a plasmon device having a structure which is less than 0.5% in total. The intensity distribution of the magnetic field when the opposite SPP mode is applied to the designed plasmon device is as shown in FIG. 9, and it can be confirmed that the beat or the like caused by reflection or the like is very weak.

In the plasmonic device 1 having the structure proposed in the present invention, only one output mode can be released for the input mode. This means that the design of the optical system can be simplified because it can reduce the need for various filters and optical isolators to eliminate the incidental noise. In addition, since the structure according to the present invention is composed of only a combination of parts having an extremely simple shape, there is an advantage that the shape is much simpler than the shape optimization technique. Finally, since the mode conversion device is a resonance structure as a whole, the overall length can be very short, which is advantageous for miniaturization.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It should be understood that various modifications may be made by those skilled in the art without departing from the spirit and scope of the invention.

1: Plasmonic element
100: Body
200: central waveguide
300: first filter
310: first vertical waveguide
320: second vertical waveguide
400: Converter
500: second filter

Claims (10)

In a plasmonic device for converting an antisense SPP mode into a symmetric SPP mode and transmitting the same,
A body made of a metal material having a predetermined permittivity;
A central waveguide extending in one direction through the inside of the body and propagating SPP;
A first filter formed on the central waveguide; Converter; And a second filter,
Wherein the central waveguide is composed of a first dielectric having a predetermined first dielectric constant value so that the SPP propagates,
The converter being located between the first filter and the second filter,
Said first filter blocking transmission of a symmetric SPP mode and passing an opposite SPP mode,
The second filter intercepts the transmission of the anti-SPP mode and passes the symmetric SPP mode,
The converter converts a counter-SPP mode to a symmetric SPP mode. The method according to claim 1,
Wherein the first filter comprises:
A vertical waveguide having a predetermined length in a direction perpendicular to the extending direction of the central waveguide and a predetermined width in a direction in which the central waveguide extends,
Wherein the vertical waveguide extends symmetrically with respect to the extending direction of the central waveguide in both vertical directions. The method according to claim 1,
The converter includes:
And a groove having a predetermined depth in the one vertical direction and a predetermined width in the extending direction of the central waveguide with respect to the extending direction of the central waveguide. The method according to claim 1,
Wherein the second filter comprises:
A second dielectric having a predetermined thickness in a direction extending from the central waveguide and having a second dielectric constant,
Wherein the second permittivity value is smaller than the first permittivity value. The method according to claim 1,
Wherein the first filter and the converter are spaced apart from each other with a first interval,
Wherein the converter and the second filter are spaced apart from each other at a second interval. 6. The method of claim 5,
The size of the first gap and the second gap,
Wherein the reflection coefficient of the opposite-SPP mode of the entire plasmonic device to be propagated in the opposite-sampling SPP mode from the first filter to the second filter is zero. A body made of a metal material having a predetermined permittivity;
A central waveguide extending in one direction through the inside of the body and propagating SPP;
A first filter formed on the central waveguide; Converter; And a second filter,
Wherein the central waveguide is composed of a first dielectric having a predetermined first dielectric constant value so that the SPP propagates,
Wherein the converter is located between the first filter and the second filter, the first filter and the converter are spaced apart from each other with a first distance, and the converter and the second filter are spaced apart from each other by a second distance Lt; / RTI &
Wherein the first filter comprises a vertical waveguide having a predetermined length in a direction perpendicular to the extending direction of the central waveguide and a predetermined width in the extending direction of the central waveguide, Extend symmetrically with respect to each other in the vertical direction on both sides to block the transmission of the symmetric SPP mode and pass the opposite SPP mode,
The second filter has a second dielectric constant value smaller than the first dielectric constant and has a predetermined thickness in the extending direction of the central waveguide, and is formed of a second dielectric material to block the transmission of the opposite SPP mode and pass the symmetric SPP mode ,
Wherein the converter comprises a groove having a predetermined depth in a direction perpendicular to the extending direction of the central waveguide and having a predetermined width in the extending direction of the central waveguide to convert the opposite SPP mode into the symmetric SPP mode ,
A method of manufacturing a plasmonic device for converting an antisense SPP mode into a symmetric SPP mode and transmitting the same,
(a) determining a length and a width of a vertical waveguide constituting the first filter;
(b) determining a thickness of the second filter;
(c) determining the width and depth of the converter;
(d) determining a value of the interval 1 satisfying Equation (1);

(1)
(

: The left reflection coefficient for the antiphase SPP mode of the block binding the first filter and the converter,

: Antilogarithm of the block binding the first filter and converter The right reflection coefficient for the SPP mode

: Transmission coefficient for counter-tangent SPP mode of the first filter and converter-bound block)
(e) substituting the value of the interval 1 determined in the step (a) into the following equation 2, and determining the value of the interval 2 so that R becomes zero.

(2)
(

: The phase shift experienced by the anti-SPP mode reflected by the second filter
: Electromagnetic wave in SPP mode

: Size of second interval) 8. The method of claim 7,
The step (a)
And the transmission amount of the symmetric SPP mode is changed by changing the width and the length of the vertical waveguide so as to minimize the transmission amount of the symmetric SPP mode and to secure the transmission amount of the opposite SPP mode, / RTI > 8. The method of claim 7,
The step (b)
And a thickness value of the second filter that allows the transmission amount of the symmetric SPP mode to have a maximum value in accordance with the transmission amount of the symmetric SPP mode for the second filter exhibiting a vibration mode due to Fabry-Perot resonance,
Wherein the thickness of the second filter is selected as a minimum thickness value of thickness values equal to or larger than a critical thickness at which the opposite SPP mode is cut off. 8. The method of claim 7,
The step (c)
Simulating the transmittance of the symmetric SPP mode with respect to the incident opposing SPP mode by varying the width and depth of the converter and selecting the width and depth of the converter according to the conversion efficiency.

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