KR101763229B1

KR101763229B1 - Selective emitter based on surface plasmon resonance

Info

Publication number: KR101763229B1
Application number: KR1020160019347A
Authority: KR
Inventors: 최민정; 김경식; 안준모
Original assignee: 국방과학연구소
Priority date: 2016-02-18
Filing date: 2016-02-18
Publication date: 2017-07-31

Abstract

The present invention relates to a radiator having a radiation characteristic in a band outside the detection range of an infrared camera so as to be applicable to infrared stealth technology, the radiator being formed on the structure and including a plurality of cogwheel-like metal patterns, A hole may be formed in the plurality of metal patterns.

Description

TECHNICAL FIELD [0001] The present invention relates to a selective plasmid based on surface plasmon resonance (SELECTIVE EMITTER BASED ON SURFACE PLASMON RESONANCE)

The present invention relates to a radiator having frequency-selective light-radiating properties in the infrared band resulting from the plasmonic resonance phenomenon of periodically arranged metal nanostructures.

Generally, since the weapon system such as a tank engine radiates black body at a high temperature of 800K, infrared (IR) camera technology for detecting infrared rays of 3 to 5 μm and 8 to 12 μm is widely used as night detection technology which is the most central for military purposes have. As a stealth technology to cope with such a detection technique, a technique using an 'optional emitter' which induces radiation in a band outside the sensing range of the IR camera has been developed.

One of them is a method of using a plasmonic photonic crystal. The plasmonic photonic crystal is a technology that utilizes a plasmon phenomenon that causes resonance phenomenon by coupling free electrons inside a metal structure with electromagnetic waves incident on a material to which crystallinity is given by periodically arranging a metal structure. As a result, And absorbs most of the water. On the other hand, Kirchhoff's law allows the plasmonic resonance structure to be used as a selective emitter, since the absorptivity and the emissivity of an object have the same value in a thermal equilibrium state.

Various techniques have been proposed as a method for changing the wavelength or frequency characteristic of an incident electromagnetic wave using a periodic structure. Korean Patent Application No. 10-1408306 is configured to pass or reflect an electromagnetic wave having a specific frequency with a conductor or slot periodically arranged on a dielectric substrate, and a cross dipole or a circular ring And the frequency characteristics can be changed by adjusting the shape of the antenna. Although this technique has the advantage of adjustable frequency characteristics, it can not be used in the infrared band because it operates in the radio band of about 1 to 8 GHz due to the size of materials and structure. A similar prior art is Korean Patent Application No. 10-2011-0069426.

Korean Patent Application No. 10-2012-0143600 discloses an infrared detector including a surface plasmon resonator that resonates in the infrared region. This method is designed to absorb a wide range of infrared wavelengths with only one resonator using a metal structure that resonates in multiple resonance modes. However, since it is intended to absorb light of a wide band, it is not suitable for changing the frequency characteristic. Since the absorption region is 7 ~ 15 탆, the radiation region covers the middle infrared region of the same wavelength and can be detected by the military infrared ray detector.

A prior invention for a metal radiator is International Application No. PCT / EP2012 / 056749. This method places the layered structure at the bottom of the selective radiation to change the radiation properties and changes the roughness of the specific layer through a coating or the like. This method is similar to the present invention in that it is a radiator using a plasmonic resonance phenomenon. However, since the operating band is 600 to 700 nm and the method of changing the lower layer structure is used instead of changing the radiation itself, There is difficulty in transcription, so the possibility of practical application is not high.

As described above, although there exist a plurality of methods for frequency selective surface structure in the prior arts, most of them have operating range of the propagation region by using an antenna or a SRR (Split Ring Resonator). Also, the prior art related to the periodic structure using the plasmonic resonance phenomenon is also not easy to apply to the infrared stealth technology because the operating wavelength stays in the mid-infrared range or the visible range.

It is an object of the present invention to provide a frequency selective radiator of a sawtooth pattern integrated pattern and a radiator having a radiation characteristic in a band outside the detection band of an infrared camera so as to be applicable to infrared stealth technology.

It is also an object of the present invention to provide a photocopier which exhibits a high efficiency of photocopying characteristics as compared with a conventional surface plasmon resonance-based plasmonic photocopier, and which can intentionally control a photocopy band and a bandwidth.

It is also an object of the present invention to provide a large-area nano-processing method overcoming the limitations of conventional nano patterning methods such as E-beam lithography and focused ion-beam (FIB).

A radiator according to an embodiment of the present invention is a surface plasmon resonance-based frequency selective radiator, wherein the radiator is formed on a structure and includes a plurality of cogwheel-like metal patterns, Can be formed.

In an embodiment of the present invention, the metal pattern may be formed of any one of gold, silver, and copper that excites a surface plasmon.

In an embodiment of the present invention, the metal pattern may be formed in the shape of the cogs to excite the surface plasmon and increase the efficiency of the radiation, and the hole may be formed in the center of the metal pattern.

In the embodiment of the present invention, each of the gear patterns may be formed by forming a plurality of circular holes at the edges of the metal disc.

In the embodiment of the present invention, the selective frequency band and the bandwidth may be changed depending on the diameter of the gear pattern and the diameter of the hole.

In an embodiment of the present invention, the size of the metal pattern is 100 to 300 nm, and the size of the hole may be 50 nm.

In an embodiment of the present invention, the radiator may further include a plurality of metal patterns of different sizes having the holes.

The radiator according to the embodiment of the present invention is constituted by a metal disk (metal pattern) having a hole shape with a hole, and has a high-efficiency radiation frequency conversion function.

The radiator according to the embodiment of the present invention operates in the near-infrared region using the plasmonic resonance phenomenon, unlike the existing frequency-selective surface structure that operates mainly in the electromagnetic wave band.

Since the design parameters such as the diameter and height of the metal disc and hole of the radiator according to the embodiment of the present invention can be controlled, the peak frequency and the bandwidth to be copied by the selective radiator can be controlled. Do. Therefore, the present invention can be effectively applied to various technologies such as improvement of efficiency of a solar cell through control of an emissivity, a frequency selective absorber, and a light source having a high luminous efficiency, in addition to the IR stealth technology as a primary object.

FIG. 1 is a diagram illustrating the concept of infrared (IR) stealth technology using an optional radiator based on a plasmonic photonic crystal material.
Fig. 2 is a schematic diagram of an optional copying device (frequency selective copying device) according to an embodiment of the present invention.
3 is a top view of an optional radiator (frequency selective radiator) according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating an infrared (IR) region emissivity spectrum of a gear-shaped metal pattern having holes simulated using a finite difference time-domain method; FIG.
FIG. 5 is an exemplary view showing a method of widening the radiation band of the selective radiator by using a metal disk (metal pattern) having the shape of a gear of a complex size.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like or similar elements are denoted by the same reference numerals, and redundant description thereof will be omitted. In the following description of the embodiments of the present invention, a detailed description of related arts will be omitted when it is determined that the gist of the embodiments disclosed herein may be blurred. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. , &Lt; / RTI > equivalents, and alternatives.

The present invention relates to a radiator having a frequency selective radiation characteristic in the infrared band resulting from a plasmonic resonance phenomenon of a periodically arranged metal nanostructure. More particularly, the present invention relates to a radiator having an array of holes arranged inside a saw- Design of near-infrared band selective radiator using combined metal disc-hole integration pattern, and control method of operating frequency band by controlling size of disc and hole. This optional photocopier suppresses the radiation of mid-infrared wavelengths (3 to 5 μm, 8 to 12 μm) used in thermal security surveillance for military purposes and various other purposes, and selectively suppresses the near-infrared wavelengths designed to reduce the probability of infrared- It can be applied as an infrared stealth device.

The present invention provides a frequency selective plasmonic radiator in the form of a combination of serrated disk arrays and hole arrays. The metal disk array has been widely developed as a device for causing local surface plasmon resonance along with nanoprobes, nano dots and the like, and it is relatively easy to produce a pattern, which is highly likely to be used in practical applications. On the other hand, since the serrations and hole arrays themselves are nanostructures that cause local surface plasmon resonance, they further amplify the size of the dense electromagnetic field, thereby increasing the overall optical absorption and emissivity. For this reason, the selective radiator of the serrated metal disc-hole integrated structure has a higher emissivity than the radiator of the simple metallic disc structure. In addition, the resonance frequency can be controlled according to the characteristics of the plasmonic resonator. In the case of the serrated metal-disc integrated pattern, the range of the frequency control and the degree of freedom can be increased by controlling the size of the metal disc and the hole.

The selective photoresist of the present invention is fabricated through colordial lithography and etching using an AAO (Anodized Aluminum Oxide) mask. This is a technology that can reproduce patterns in a large area at a low cost. A metal disc is formed by physical and chemical etching using a single layer of nano-spheres of several hundred nanometers on a metal-deposited substrate as a mask. Next, an AAO mask having a hole of several tens of nanoscale is placed on a metal disc, and then the metal disc is etched again to complete a sawtooth-shaped metal pattern (metal disc) in which the hole is etched in the inner edge of the metal disc.

Figure 1 illustrates the concept of infrared stealth technology using an optional photocell based on a plasmonic photonic crystal material and is an example of using the present invention for IR stealth purposes. Normal black body thermal radiation has strong radiation intensity at 3 ~ 5μm, 8 ~ 12μm, which can be detected by infrared (IR) camera because radiation occurs in wide band of mid infrared range. However, by using the selective radiator of the present invention, it is possible to detect a small radiation intensity in the detection band.

FIG. 2 is a schematic diagram of an optional copying device (frequency selective copying device) according to an embodiment of the present invention, and FIG. 3 is a top view of an optional copying device (frequency selective copying device) according to an embodiment of the present invention.

An optional radiator (frequency selective radiator) 20 according to an embodiment of the present invention is a surface plasmon resonance-based frequency selective radiator, which is formed on a layered structure 10 and is composed of a plurality of cogwheel-like metal patterns, A hole is formed at the center of each metal pattern.

As shown in Figs. 2 and 3, the radiation body 20 constituted by a plurality of gear-shaped metal patterns (metal discs) 21 having holes 22 can be formed have. The embodiment of FIG. 1 realizes an improved photocopier than the case of using only a single layer substrate in terms of the radiation ratio by arranging the selective radiation body 20 on the upper part of the metal-dielectric-metal plate. In an apparatus requiring optical transmission, the selective radiation body 20 can be arranged on a transparent substrate such as glass.

The radiator 20 constituted by a plurality of toothed wheel-shaped metal patterns (metal discs) 21 having the holes 22 has a first metal layer 11, a second metal layer 13, a first metal layer 11, And a dielectric layer (or insulating layer) 12 formed between the second metal layers 13.

The metal pattern (metal disc) 21 is made of a metal material capable of exciting plasmons, and may be formed of any one of gold, silver, and copper.

The metal pattern (metal disc) 21 can be formed (formed) by forming a plurality of circular holes at the edges of the metal disc.

The selective frequency band and the bandwidth are changed according to the adjustment of the diameter and the height of the toothed metal pattern 21 and the hole 22.

The size of the metal pattern 21 may be 100 to 300 nm, and the size of the hole 22 may be about 50 nm.

FIG. 4 is a diagram illustrating an infrared (IR) region emissivity spectrum of a gear-shaped metal pattern having holes simulated using a finite difference time-domain method; FIG.

As shown in FIG. 4, the frequency selective radiation element 20 according to the embodiment of the present invention has optical characteristics such that the radiation ratio at a specific wavelength is 100% and the radiation rate at other wavelengths is substantially 0%.

By forming the hole 22 in the center of the saw-toothed metal disc 21, the local surface plasmon effect can be increased and the emissivity at the resonance wavelength can be further improved. Further, since the width of the resonance spectrum peak is narrow and the frequency selective characteristic is excellent and the resonance wavelength band can be adjusted by controlling the size of the arrangement of the metal disc 21 and the hole 22, the optimum radiation band can be selected according to the purpose of use have. The embodiment of FIG. 2 is an example in which the selective photocatalyst 20 of the present invention is selectively used in the wide band having energy above the bandgap of gallium antimonide for use with gallium antimonide (GaSb) It is designed to copy. Since the light having a wavelength equal to the band gap energy of gallium antimonide is 1.73 mu m, the energy conversion efficiency can be improved by selectively radiating only the energy of the solar cell band gap or more by inducing radiation near the shorter wavelength of 1.6 mu m.

FIG. 5 is an exemplary view showing a method of widening the radiation band of the selective radiation body 20 by using a complex-sized, gear-shaped metal disc (metal pattern) together.

As shown in FIG. 5, when one optional radiator is formed by using a combination of the metal patterns of the toothed wheels having holes of various sizes, the resonance bands occurring in each one are combined to obtain a broadband radiation spectrum. 5, the size of the metal disc (metal pattern) 21 is set to 110, 180, and 240 nm, and holes 22 of the same size are combined in the discs to form a wide resonance band of 900 to 1800 nm . By using this method, the content of the present invention can be flexibly applied not only to the purpose of stealth but also to various optical devices such as a solar cell.

INDUSTRIAL APPLICABILITY As described above, the radiator according to the embodiment of the present invention is composed of a metal disk (metal pattern) having a hole with a hole, and has a high-efficiency radiation frequency conversion function.

The foregoing detailed description should not be construed in all aspects as limiting and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

Claims

A surface-plasmon resonance-based, frequency-selective radiation source,
A plurality of metal patterns formed on the structure and in the form of a hexagonal cogwheel, wherein the plurality of metal patterns are formed with holes,
Wherein the metal pattern is formed in the shape of a cogwheel to excite the surface plasmon and increase the efficiency of the radiation, the hole is formed in the center of the metal pattern,
Each of the gear patterns is formed by forming a plurality of circular holes at the edges of the metal disc,
Wherein the selective frequency band and the bandwidth are changed according to the adjustment of the diameter and the height of the toothed metal pattern and the hole.

The metal pattern according to claim 1,
Silver, and copper that excite surface plasmons.

delete

The photocopier according to claim 1, wherein the size of the metal pattern is 100 to 300 nm, and the size of the hole is 50 nm.

The apparatus according to claim 1,
Further comprising a plurality of metal patterns of different sizes having said holes.