• 한국광학회:학술대회논문집
• /
• 한국광학회 2002년도 하계학술발표회
• /
• pp.162-163
• /
• 2002

1-D photonic band-gap structure is identified in a cholesteric liquid crystal system. The optical transmission spectrum is measured and compared with the theoretical analysis. Nonlinear transmission is measured near the band edge. Also 3-D photonic band-gap structures are fabricated from dielectric colloidal polystyrene beads through a centrifuge method. The fabricated photonic crystals exhibit opalescent colors under white light and show a clear diffraction peak dependent on the incident angle of the light beam. Also the scanning electron microscope image was taken to verify the face-centered cubic crystal structure. Bragg's law and Snell's law are employed to describe the position of angle resolved diffraction peaks. It was shown that the optically deduced effective refractive index and lattice constants were in good agreement with the crystal structure identified by scanning electron microscope.

• 통합자연과학논문집
• /
• 제2권1호
• /
• pp.41-44
• /
• 2009

Photonic crystals containing multiple rugate structure are prepared by electrochemical etchings. Typically etched rugate PSi prepared in this study. Etching is carried out in a Teflon cell by using a two-electrode configuration with a Pt mesh counter electrode. They exhibit sharp photonic band gaps in the optical reflectivity spectrum. This reflectivity can be tuned to appear anywhere in the visible to near-infrared spectral range, depending on the programmed etch waveform. We study the method of full width half maxima and reflectivity index control by using amplitude.

• 한국통신학회논문지
• /
• 제26권12B호
• /
• pp.1754-1757
• /
• 2001

본 논문에서는 IMT-2000, 무선LAN, PCS 대역인 R-band에서 Coplanar waveguide (CPW)와 Photonic Bandgap (PBG)을 이용한 증폭기를 설계 및 제작하였다. 기존 마이크로스트립을 이용한 증폭기에만 적용되던 PBG 기술을 처음으로 CPW를 이용한 증폭기에 적용하여 출력효율 및 IMD를 측정하였다. PBG구조는 매칭 네트웍구성을 위해 최적화되었으며 이로인해 입출력 반사손실이 최소화 되도록 PBG 구조가 정합되었다. 측정결과 CPW구조에 새롭게 적용퇸 PBG구조를 이용하여 동일 IMD에 대해 15%의 출력효율과 동일 출력에 대해 IMD 4.5dB 향상을 얻을 수 있었다.

• 한국전기전자재료학회논문지
• /
• 제23권2호
• /
• pp.137-142
• /
• 2010

A plane wave expansion method (PWEM) was applied for photonic band structure calculation. We examined zero group velocity modes in photonic crystal. The zero group velocity modes were obtained at the second band along F-K direction. We expanded higher order Brillouin zone (BZ) to find the locations of zero group velocity modes and to investicate their properties. We found twelve locations, inside the first Brillouin zone, where the group velocities became zero. Also, we calculated band structure and group velocity in off-plane configuration.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.1405-1407
• /
• 2009

We prepared polystyrene-b-poly(2-vinyl pyridine) (PSb-P2VP) lamellar films which is hydrophobic block-hydrophilic polyelectrolyte block polymer have 57 kg/mol-b-57 kg/mol. The result of UV-visible absorption spectra supported that effect of poly(ethylene oxide) on the band gap tuning of PS-P2VP photonic gel like salt effect.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
• /
• pp.105-108
• /
• 2007

Chiral liquid crystals exhibit band-gap structures responsive to electrical and optical fields, providing wide-ranging opportunities for photonics applications. We discuss three aspects of this technology: optics of chiral nematic devices and removal of pitch jumps; optical switching of chiral nematic materials; and using novel phases in photonic devices.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2003년도 하계학술발표회
• /
• pp.226-227
• /
• 2003

광자 크리스탈 (Photonic Crystals)은 서로 다른 유전체의 주기적인 구조로 이루어져 있으며, 전자기파가 특정한 주파수 범위에서 전파하지 못하고 차단되는 영역인 광자 밴드갭 (Photonic Band Gap)이 존재한다. 이러한 광자 밴드갭의 존재로 인하여 빛의 흐름을 조절할 수 있다는 점 때문에 반사거울, 휘어진 도파로(bent waveguide), 레이저, 채널 드롭핑 필터(channel dropping filter) 등 여러 가지 다양한 분야에 응용될 수 있다. (중략)

• 한국고분자학회지:고분자과학과기술
• /
• 제15권3호
• /
• pp.317-326
• /
• 2004

광자 (photon)를 이용하여 정보의 전달, 표시, 감지 그리고 저장이 가능한 다양한 형태의 소자들은 현재 그 주를 이루고 있는 전자 (electron)가 매개인 소자를 대체할 수 있는 가능성을 가지고 활발히 연구되고 있다. 전자의 움직임은 재료 내에 주기적으로 배열되어 있는 원자나 분자의 결정구조에 의해 제어된다. 이는 전도밴드 (conduction band)와 원자가 밴드(valance band) 사이에 존재하는 전자 밴드갭 (electronic band gap)을 조절함으로써 가능하다. 이와 유사한 개념으로 광자의 움직임은 유전체의 주기적인 배열을 통해서 가능함이 제안되었다. 규칙적인 유전체의 결정구조를 가진 재료에 빛이 조사되었을 때, 그 재료를 통과하지 못하는 특정파장이 결정되며 이를 광자 밴드갭 (photonic band gap: PBG)이라 한다. (중략)

• Journal of the Optical Society of Korea
• /
• 제7권1호
• /
• pp.38-41
• /
• 2003

We present an analysis of highly-dispersive guided modes of two-dimensional photonic crystal waveguides. By the plane ave expansion method, band structures and mode profiles of two-dimensional photonic crystal waveguides are obtained. It is found that guided modes have very small group velocities and very large group velocity dispersions in the region near the f-point and in the region near the Brillouin zone edge. Especially, the group velocity dispersions are found to be millions of times larger than that of a conventional optical fiber. The contributions of the transverse resonance formed by two photonic band gap reflectors and the standing wave mode formed by periodic structures are discussed. We conclude that the highly-dispersive characteristics originate from the resonator-like aspect of the photonic crystal waveguide.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.134.2-134.2
• /
• 2014

Photonic crystal solar cells have the potential for addressing the disparate length scales in polymer photovoltaic materials, thereby confronting the major challenge in solar cell technology: efficiency. One must achieve simultaneously an efficient absorption of photons with effective carrier extraction. Unfortunately the two processes have opposing requirements. Efficient absorption of light calls for thicker PV active layers whereas carrier transport always benefits from thinner ones, and this dichotomy is at the heart of an efficiency/cost conundrum that has kept solar energy expensive relative to fossil fuels. This dichotomy persists over the entire solar spectrum but increasingly so near a semiconductor's band edge where absorption is weak. We report a 2-D, photonic crystal morphology that enhances the efficiency of organic photovoltaic cells relative to conventional planar cells. The morphology is developed by patterning an organic photoactive bulk heterojunction blend of Poly(3-(2-methyl-2-hexylcarboxylate) thiophene-co-thiophene) and PCBM via PRINT, a nano-embossing method that lends itself to large area fabrication of nanostructures. The photonic crystal cell morphology increases photocurrents generally, and particularly through the excitation of resonant modes near the band edge of the organic PV material. The device performance of the photonic crystal cell showed a nearly doubled increase in efficiency relative to conventional planar cell designs. Photonic crystals can also enhance performance of other optoelectronic devices including organic laser.