• 한국세라믹학회지
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• 제54권5호
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• pp.349-365
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• 2017

Graphene has attracted a lot of attentions due to the unique electrical and optical properties. Compared with the noble metal plasmons in the visible and near-infrared frequencies, graphene can support surface plasmons in the lower frequencies of terahertz and mid-infrared and it demonstrates an extremely large confinement at the surface because of the particular electronic band structures. Especially, the surface conductivity of graphene can be tuned by either chemical doping or electrostatic gating. These features make graphene a promising candidate for plasmonics, biosensing and transformation optics. Furthermore, the combination of graphene and metasurfaces presents a powerful tunability for exotic electromagnetic properties, where the metasurfaces with the highly-localized fields offer a platform to enhance the interaction between the incident light and graphene and facilitate a deep modulation. In this paper, we provide an overview of the key properties of graphene, such as the surface conductivity, the propagating surface plasmon polaritons, and the localized surface plasmons, and the hybrid graphene/metasurfaces, either metallic and dielectric metasurfaces, from terahertz to near-infrared frequencies. Finally, there is a discussion for the current challenges and future goals.

• Current Applied Physics
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• 제18권11호
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• pp.1381-1387
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• 2018

One dimensional (1D) grating has been fabricated (using focused ion beam) on 50 nm gold (Au) film deposited on higher refractive index Gallium phosphate (GaP) substrate. The sub-wavelength periodic metal nano structuring enable to couple photon to couple with the surface plasmons (SPs) excited by them. These grating devices provide the efficient control on the SPs which propagate on the interface of noble metal and dielectric whose frequency is dependent on the bulk electron plasma frequency of the metal. For a fixed periodicity (${\Lambda}=700 nm$) and slit width (w = 100 nm) in the grating device, the efficiency of SPP excitation is about 40% compared to the transmission in the near-field. Efficient coupling of SPs with photon in dielectric provide field localisation on sub-wavelength scale which is needed in Heat Assisted Magnetic recording (HAMR) systems. The GaP is also used to emulate Vertical Cavity Surface emitting laser (VCSEL) in order to provide cheaper alternative of light source being used in HAMR technology. In order to understand the underlying physics, far-and near-field results has been compared with the modelling results which are obtained using COMSOL RF module. Apart from this, grating devices of smaller periodicity (${\Lambda}=280nm$) and slit width (w = 22 nm) has been fabricated on GaP substrate which is photoluminescence material to observe amplified spontaneous emission of the SPs at wavelength of 805 nm when the grating device was excited with 532 nm laser light. This observation is unique and can have direct application in light emitting diodes (LEDs).

• 반도체디스플레이기술학회지
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• 제18권3호
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• pp.105-109
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• 2019

Plasmons have conductive properties using the effect of amplifying magnetic and electric fields around metal particles. The collective movement of free electrons in metal particles induces and produces the generation of plasmon. Because the plasmon is concentrated on the surface of the nanoparticles, it is also called the surface plasmon. The polarizing effect of plasma on the surface is similar to the principle of surface currents occurring in insulators. In this study, it was found the conditions under which plasma is produced in SiOC insulators and studied the electrical properties of SiOC insulators that are improved in conductivity by plasmons. Due to the heat treatment temperature of thin film, plasma formation was shown differently, metal particles were used with normal aluminium, SiOC thin films were treated with heat at 60 degrees, conductivity was improved dramatically, and heat treatment at higher temperatures was found to be less conductivity.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.225-225
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• 2013

Nanostructured noble metals have been attractive for their unusual optical properties and are widely utilized for various purposes. The optical properties mainly originating from collective electron oscillation can assist direct energy conversion via surface plasmon resonances. Here, we investigated the effect of surface plasmons of silver nanowires on the generation of hot electrons. It is reported that the surface plasmons of silver nanowires exhibit longitudinal and transverse modes, depending on the aspect ratio of the nanowires. In order to measure the hot electron flow through the metallic nanowires, chemically modified Au/TiO2 Schottky diodes were employed as the electric contact. The silver nanowires were deposited on a Au metal layer via the spray method to control uniformity and the amount of silver nanowire deposited. We measured the hot electron flow generated by photon absorption on the silver nanowires deposited on the Au/TiO2 Schottky diodes. The incident photon-to-current efficiency was measured a function of the photon energy, revealing two polarization modes of siliver nanowires: transverse and longitudinal modes. UV-Vis spectra exhibited two polarization modes, which are also consistent with the photocurrent measurements. Good correlation between the IPCE and UV-vis measurements suggests that hot electron measurement on nanowires on nanodiodes is a useful way to reveal the intrinsic properties of surface plasmons of nanowires.

• Current Optics and Photonics
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• 제7권1호
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• pp.97-103
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• 2023

In this paper, we propose Babinet-principle-inspired metasurfaces for strong resonant enhancement of local magnetic fields. The metasurfaces are designed as complementary structures of original metasurfaces supporting the local enhancement of electric fields. We show numerically that the complementary structures can support spoof magnetic surface plasmons that induce strong local magnetic fields without sacrificing the deep sub-wavelength-thick nature of the metasurface. By introducing a periodic array of metallic rods in the proximity of the metasurfaces, we demonstrate that a resonant enhancement of the local magnetic fields, more than 80 times the amplitude of an incident magnetic field, can emerge from a resonance of the spoof magnetic surface plasmons.

• 한국광학회지
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• 제22권6호
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• pp.269-275
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• 2011

회절한계 이하의 모드 크기를 가지는 금속-유전체 혼합 광도파로 구조를 제안하고자 한다. 제안된 혼합 광도파로는 금속 나노선이 유전체 평면 위에 놓인 구조로서, 금속선과 유전체 사이에 구속된 파장보다 작은 크기의 표면-플라즈몬 모드의 특성을 기존의 유전체 나노선을 이용하는 구조와 비교 분석하였다. 두 도파로의 모드 크기와 전파 거리는 나노선의 직경이 큰 경우에는 비슷한 경향을 보이나, 직경이 작아짐에 따라 서로 상이한 값을 가진다. 회절 한계보다 100배 이상 작은 모드를 갖는 파장길이의 나노 공진기 구현을 위해서는 제안된 금속 나노선-유전체 광 도파로 구조가 적합함을 보였다.

• Journal of the Optical Society of Korea
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• 제8권1호
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• pp.6-12
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• 2004

Diffraction Bragg gratings consisting of metal (silver) nanoparticles are generated inside a soda-lime glass substrate. After ion-exchanging and annealing processes in the glass, the silver nanoparticles are first formed with the particle diameters of 10 nm ∼ 30 nm. By interfering two CW laser beams at ∼ 60 ${\mu}{\textrm}{m}$ deep under the surface of the nanoparticles-dispersed glass, Bragg gratings with thickness of 15 ${\mu}{\textrm}{m}$ and period of 3.5 ${\mu}{\textrm}{m}$ are generated. Diffraction efficiency of the gratings formed by two TE-polarized beams is three times higher than that by two TM-polarized beams. From this polarization dependence, we have found that strong coupling of the surface plasmons induced on the metal particles may contribute dominantly to generate the diffraction grating.

• Current Optics and Photonics
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• 제4권2호
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• pp.134-140
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• 2020

A significant enhancement of the magneto-optical Faraday rotation and extraordinary optical transmission (EOT) in the cascaded double-fishnet (CDF) structure with periodic rectangular apertures is theoretically predicted by using the extended finite difference time domain (FDTD) method. The results demonstrate that the transmittance spectrum of the CDF structure has two EOT resonant peaks in a broad spectrum spanning visible to near-infrared wavebands, one of them coinciding with the enhanced Faraday rotation and large figure of merit (FOM) at the same wavelength. It is most important that the resonant position and intensity of the transmittance, Faraday rotation and FOM can be simply tailored by adjusting the incident wavelength, the thickness of the magnetic layer, and the offset between two metallic rectangular apertures, etc. Furthermore, the intrinsic physical mechanism of the resonance characteristics of the transmittance and Faraday rotation is thoroughly studied by investigating the electromagnetic field distributions at the location of resonance. It is shown that the transmittance resonance is mainly determined by different hybrid modes of surface plasmons (SPs) and plasmonic electromagnetically induced transparency (EIT) behavior, and the enhancement of Faraday rotation is mostly governed by the plasmonic electromagnetically induced absorption (EIA) behavior and the conversion of the transverse magnetic (TM) mode and transverse electric (TE) mode in the magnetic dielectric layer.

• 한국광학회지
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• 제19권1호
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• pp.73-79
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• 2008

금속선 도파로 면과 금속 평면이 수직으로 적층된 장거리 표면-플라즈몬 도파로 구조를 제안하였으며, 표면-플라즈몬 모드의 특성을 유전체의 굴절율과 두께 변화에 대하여 이론적으로 분석하고 실험적으로 검증하였다. 위층의 금속선 도파로를 S-곡선과 Y-분기 형태로 변형시킨 이중-금속 도파로를 제작하여, 제안된 이중-금속 도파로 구조의 광 소자 응용 가능성을 살펴보았다. 제안된 이중금속 구조에서는 도파로 코어에 해당하는 두 금속 박막 사이의 유전체 굴절률을 임의로 선택하여도 장거리 표면 플라즈몬 모드가 존재할 수 있으며, 표면-플라즈몬 모드의 전파거리는 두 금속 박막 사이의 유전체 두께를 조절함으로써 증가시킬 수 있다. 또한, 이중-금속 도파로는 표면-플라즈몬을 전달할 뿐만 아니라, 삽입된 코어 유전체에 전압 및 전류를 인가하기에도 매우 적합한 구조로서, 표면-플라즈몬 능동소자 및 비선형 소자 구현에 많은 가능성을 열어줄 것으로 기대된다.

• 한국광학회지
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• 제15권1호
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• pp.51-55
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• 2004

표면 플라즈몬은 금속 표면에 존재하는 자유전자의 밀도파이며, 광자와 결합하여 존재한다. 본 논문에서는 근접장 주사 광학 현미경을 구성하고 이를 이용하여 표면에서 지수함수적으로 감소하는 표면 플라즈몬과 두 표면 플라즈몬에 의한 간섭무늬를 측정하였다. 표면 플라즈몬은 표면의 작은 광학적 분포에도 민감하게 변화하여, 광학 탐침이 금속 표면에 접근함에 따라서 표면 플라즈몬의 공명 조건에 영향을 준다. 이로 인해 광학 탐침이 금속 표면으로부터 약 250nm 떨어진 곳에서 광의 세기가 최대가 됨을 확인하였다.