• 한국광학회지
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• 제27권6호
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• pp.229-232
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• 2016

마이크로 갭을 포함하는 테라헤르츠파 메타물질을 이용하면 공명주파수 근방의 투과 스펙트럼 변화를 관측함으로써, 높은 감도로 마이크로 크기의 곰팡이, 박테리아 등의 미생물을 검출할 수 있다. 공명주파수의 스펙트럼 변화폭은 미생물의 굴절률 및 마이크로 갭에 위치한 미생물의 개수에 크게 의존한다. 테라헤르츠 메타물질을 통해 다양한 미생물들을 검출하였으며, 또한, 세척 과정을 통해 센서의 재사용이 가능함을 보였다. 유한차분 시간영역 전산모사를 이용하여 메타물질 공명주파수의 미생물 개수 및 굴절률 의존성을 확인하고 실험결과를 검증하였다.

• Current Optics and Photonics
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• 제5권4호
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• pp.370-374
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• 2021

Corals are the remains of animals that grow on warm beaches. They have been used as decorative jewels because of their variety of colors, and as medicinal materials for treating cancers, AIDS, and other therapeutic uses because of their chemical elements. Corals are mainly composed of calcium carbonate (CaCO₃) and have many air pores, tens to hundreds of micrometers in size. The refractive indices and absorption coefficients of dried sliced staghorn corals are investigated using terahertz time-domain spectroscopy. The measured values are similar to those for CaCO₃, as expected. It is observed that a sample with a microstructure formed by air pores can guide terahertz waves. The dispersion, effective index, and loss of the guiding modes of coral core surrounded by five triangular air pores are numerically calculated. The simulated spatial distribution of the electric field of the guide mode at 1.25 THz shows the mode to be tightly confined to the core.

• 센서학회지
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• 제27권5호
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• pp.317-327
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• 2018

THz 시간 영역 분광학(TDS)은 이제 성숙한 분야가 되었고, 그 기술은 전 세계적으로 수백 개의 연구실에서 사용되고 있지만, THz 시스템의 개선에 대한 여지는 아직 많이 남아있다. 도전과제의 핵심은 모드-잠김 에지 방사(edge emitting) 반도체방출 반도체 레이저와 광전도 반도체 양자 구조의 개선이다. 또한 대량 생산을 위한 기술과 3D 프리팅과 같은 혁신적인 제조 기술도 매우 효과적이다. 최근에 상용제품으로 출시된 OSCAT 시스템과 ASOPS 시스템을 이용하여 분광/영상기법을 반도체 패키지 칩에 적용하기도 하였다. 한편, THz 분광법이 정적(static)이거나 또한 시간-분해적이든 간에 모두 반도체 소재 및 반도체 나노 구조의 특성을 평가하는 데 있어서 선도적인 기법이 될 것이다. 향후에는 점점 더 좁은 영역을 탐구하는 방법이나 THz 응용 시스템을 평형상태에서 벗어나게 하는 툴(tool)로써 사용될 가능성도 높다. 또한 메타(meta) 물질을 이용하여 THz 시스템에 적용할 경우, 가변 필터와 같은 순시적인 광학 부품이 가능하므로 광여기(photoexcited) 반도체 소자(신호원)으로 이용하는 구상/디자인도 할 수 있다.

• 한국광학회:학술대회논문집
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• 한국광학회 2002년도 하계학술발표회
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• pp.172-173
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• 2002

As feature sizes of circuits and devices approach 100 m and chip frequencies climb into the upper gigahertz to terahertz range, it becomes increasingly important to have a convenient method of characterizing properties of thin dielectric films in the GHz to THz frequency range [1]. To measure the dielectric and optical properties of materials at THz frequency, a TH2 time-domain spectroscopy has been utilized during past decade. (중략)

• 한국전기전자재료학회논문지
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• 제14권3호
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• pp.202-206
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• 2001

Using THz time-domain spectroscopy (THz-TDS), the power absorption, the index of refraction, and the real conductivity of silica sand are measured from 0.1[Thz] to 0.5[Thz] frequency range. It is impossible to measure the characterization of the silica sand by simple electrical measurements using mechanical contacts, e.g., Hall effect or four-point probe measurements. However, the THz-TDS technique can measure not only electrical but also optical characterization of he sample. Also this technique can measure frequency dependent results. Especially, the real conductivity was increased according to THz frequency. This is unusual material compare with metal and semiconductor materials; the measured real conductivity are not followed by the simple Drude theory.

• 한국생산제조학회지
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• 제21권6호
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• pp.1003-1007
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• 2012

A nondestructive technique would be very useful. Advanced NDE T-ray (terahertz ray) techniques of technology and instrumentation has provided a probing field on the electromagnetic spectrum. However, the T-ray is limited in order to penetrate a conducting material to some degree. Here, the T-ray would not go through easily the CFRP composite laminates since carbon fibers are electrically conducting while the epoxy matrix is not. So, investigation of terahertz time domain spectroscopy (THz TDS) was made and reflection and transmission configurations were studied for a 48-ply thermoplastic PPS(poly-phenylene sulfide)-based CFRP solid laminate. It is found that the electrical conductivity of CFRP composites depends on the direction of unidirectional fibers.

• Journal of the Optical Society of Korea
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• 제19권6호
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• pp.673-678
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• 2015

Terahertz dual-band frequency selective surface filters made by perforating two different rectangular holes in molybdenum have been designed, fabricated and measured. Physical mechanisms of the dual-band resonant responses are clarified by three differently configured filters and the electric field distribution diagrams. The design process is straightforward and simple according to the physical concept and some formulas. Due to the weak coupling between the two neighboring rectangle holes with different sizes in the unit cell, good dual-band frequency selectivity performance can be easily achieved both in the lower and higher bands by tuning dimensions of the two rectangular holes. Three samples are fabricated, and their dual-band characteristics have been demonstrated by a THz time-domain spectroscopy system. Different from most commonly used metal-dielectric structure or metal-dielectric-metal sandwiched filters, the designed dual-band filters have advantages of easy fabrication and low cost, the encouraging results afforded by these filters could find their applications in dual-band sensors, THz communication systems and other emerging THz technologies.

• Journal of the Optical Society of Korea
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• 제12권3호
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• pp.196-199
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• 2008

We have investigated spectral properties of the periodic arrays of aluminum rods and holes on papers using the terahertz time-domain spectroscopy. The size of a rod(hole) is $600{\mu}m{\times}100{\mu}m$ and the spacing is $300{\mu}m$. The samples were fabricated by a femtosecond laser micromachining system. The periodic arrays of aluminum rods exhibit high reflection around 0.25 THz when the polarization of the THz pulse is parallel to the long axis of the rod, whereas the periodic arrays of holes exhibit high transmission around 0.25 THz when the polarization of the THz pulse is perpendicular to the long axis of the hole.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.28-28
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• 2007

Ferroelectric $(Ba_{0.5}Sr_{0.5})TiO_3$ (BST) thin films of thickness 500nm were deposited on $LaAlO_3$, (LAO) substrates by at $800^{\circ}C$. BST films were characterized for structure using X-ray diffraction (XRD). The surface morphology and thickness of BST the films were characterized by atomic force microscopy (AFM) and field emission scanning electron microscope (FESEM). We measured the dielectric properties at microwave frequencies (1~3 GHz) using a symmetrical stripline resonator with shorted ends and terahertz frequencies (0.2~2.5 THz) using a time-domain terahertz spectroscopy. The real and imaginary parts of the complex dielectric constant of the BST thin films on LAO substrates were in agreement with those previously reported.

• 비파괴검사학회지
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• 제37권1호
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• pp.1-6
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• 2017

본 논문에서는 테라헤르츠파 시간분광영상시스템을 이용하여 도핑된 실리콘 웨이퍼의 물리적 특성을 측정하는 것에 관한 연구를 진행하였다. 투과모드와 $30^{\circ}$의 입사각을 가진 반사모드를 이용하여 측정하였으며 실리콘 웨이퍼의 도핑 정도는 N-type과 P-type 모두에서 $10^{14}$에서 $10^{18}$까지 다양하게 준비하였다. 그 결과, 도핑 정도와 테라헤르츠파와의 상관관계를 찾았으며 이를 이용하면 모든 경우에 대한 도핑된 실리콘 웨이퍼의 도핑 정도를 확인할 수 있다. 또한, 각 도핑된 실리콘 웨이퍼의 도핑된 두께, 굴절률, 유전율을 테라헤르츠 시간영역 파형분석을 통하여 계산할 수 있었다. 따라서, 테라헤르츠 시간분광영상화 기술은 도핑된 실리콘 웨이퍼의 굴절률과 유전율과 같은 물리적 특성뿐만 아니라 도핑 정도를 측정할 수 있는 유용한 기술이 될 것으로 기대된다.