• Korean Journal of Optics and Photonics
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• v.16 no.2
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• pp.159-161
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• 2005

We report the selective area bandgap tuning of multiple quantum well structures by an impurity free vacancy induced quantum well intermixing technique. A 3dB waveguide directional coupler was fabricated in the disordered section of an intermixed quantum well sample as a demonstration of photonic device applications.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.390-391
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• 2009

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.251-252
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• 2008

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.808-813
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• 2009

Indium nitride thin films were deposited by the radio-frequency reactive magnetron sputtering method. The indium target was sputtered by the mixture flow ratio of $N_2$ to Ar, 9:1. The effects of growth temperature on the structural, optical, and electrical properties of the films were investigated. With increasing the growth temperature, the crystallinity of the films was improved, and the crystalline size was increased. The energy bandgap for the film grown at $25^{\circ}C$ was 3.63 eV, and the bandgap showed an increasing tendency on the growth temperature. The carrier concentration, Hall mobility and electrical resistivity of the films depended significantly on the growth temperature and the maximum Hall mobility of $32.3\;cm^2$/Vsec was observed for the film grown at $400^{\circ}C$.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.2-3
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• 2001

Characteristics of two-dimensional slab photonic crystal lasers will be summarized. Room temperature c.w operation is demonstrated at 1.6 $\mu\textrm{m}$ by using InGaAsP slab-waveguide triangular photonic crystal on top of wet-oxidized aluminum oxide. Recently, 2-D PBG structures have attracted a great deal of attention due to their simplicity in fabrication and theoretical study as compared to the three-dimensional counterparts [1]. Air-guided 2-D slab PBG lasers were reported by Caltech group (2). However, this air-slab structure is mechanically fragile and thermally unforgiving. Therefore, a new structure that can remove this thermal limitation is dearly sought after for 2-D PBG laser to have practical meaning. In this talk, we report room-temperature continuous operation of 2-D photonic bandgap lasers that are thermally and mechanically stable.(omitted)

• Journal of the Optical Society of Korea
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• v.7 no.1
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• pp.34-37
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• 2003

Outside the photonic bandgap of two-dimensional square lattice photonic crystals, we found spectral regions in which light coupling from the air is forbidden. This uncoupling spectral region originates from the anisotropy of the photonic crystals. A two-dimensional square photonic crystal has a complete total bandgap (forbidden region in both TE and TM modes) with hole radius ranging from 0.15 to 0.45 times a lattice constant.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.96-98
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• 2000

Room-temperature continuous operation of two-dimensional photonic crystal lasers is achieved at 1.6 ${\mu}{\textrm}{m}$ by using InGaAsP slab-waveguide triangular photonic crystal on top of wet-oxidized aluminum oxide. The main difficulty in the realization of photonic bandgap (OBG) structures has been the nontrivial difficulties in nanofabrication, especially for 3-dimensional PBG structures. Recently, 2-D PBG structures have attracted a great deal of attention due to their simplicity in fabrication and theoretical study as compared to the three-dimensional counterparts [1]. Recently, air-gulfed 2-D slab PBG lasers were reported by Caltech group [2]. However, this air-slab structure is mechanically fragile and thermally unforgiving. Therefore, a new structure that can remove this thermal limitation is dearly sought after for 2-D PBG laser to have practical meaning. In this talk, we report room-temperature continuous operation of 2-D photonic bandgap lasers that are thermally and mechanically stable.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.6
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• pp.528-533
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• 2019

We investigated the growth of $(Al_xGa_{1-x})_2O_3$ thin films on c-plane sapphire substrates that were grown by mist chemical vapor deposition (mist CVD). The precursor solution was prepared by mixing and dissolving source materials such as gallium acetylacetonate and aluminum acetylacetonate in deionized water. The [Al]/[Ga] mixing ratio (MR) of the precursor solution was adjusted in the range of 0~4.0. The Al contents of $(Al_xGa_{1-x})_2O_3$ thin films were increased from 8 to 13% with the increase of the MR of Al. As a result, the optical bandgap of the grown thin films changed from 5.18 to 5.38 eV. Therefore, it was determined that the optical bandgap of grown $(Al_xGa_{1-x})_2O_3$ thin films could be effectively engineered by controlling Al content.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.340.1-340.1
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• 2014

본 실험에서는 Ag두께 변화에 따른 투과율과 Energy bandgap의 변화를 알아보기 위해 RF Sputter장비와 Evaporator장비를 사용하여 IGZO, ZnO, AZO OMO 구조로 Low-e 코팅된 Glass를 제작하였다. $3cm{\times}3cm$의 Corning1737 유리기판에 RF Sputtering 방식으로 Oxide layer를 증착 하였고 Evaporator장비로는 Metal layer인 Ag막을 증착하였다. Oxide layer 증착 시 RF Sputter장비의 조건은 $3.0{\times}10^{-6}Torr$이하로 하였으며, 증착압력은 $6.0{\times}10^{-3}Torr$, 증착온도는 실온으로 고정하였다. Metal layer 증착 시 Evaporator장비의 조건은 $5.0{\times}10^{-6}Torr$이하, 전압은 0.3 V, Rotate 2 rpm으로 고정하였다. 실험 변수로는 Ag 두께를 5,7,9,11,13 nm로 변화를 주어 실험을 진행하였다. 투과도 측정 장비를 사용하여 각 샘플을 측정한 결과 IGZO의 경우 가시광영역의 평균 투과율이 80% 이상이며 Ag두께가 5nm일 때부터 자외선 영역의 빛을 차단하여 low-e 특성을 나타내었다. 이는 산화물인 IGZO가 결정질인 AZO, ZnO 보다 낮은 표면거칠기를 가지기 때문이다. Ag 두께에 따른 각 물질의 Optical energy bandgap 분석결과 Ag 두께가 증가할수록 IGZO는 4.65~4.5 eV, AZO는 4.6~4.4 eV, ZnO는 4.55~4.45 eV로 Energy bandgap은 감소하였다. AFM장비를 이용하여 각 샘플의 표면 Roughness 측정 결과 Ag 두께가 증가할수록 표면거칠기도 증가하는 경향을 나타내었다.

• Korean Journal of Optics and Photonics
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• v.21 no.5
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• pp.200-205
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• 2010

We report temperature and strain sensing characteristics of two kinds of in-line fiber interferometers. One interferometer consists of a section of Hollow Optical Fiber(HOF) spliced between two Photonic Bandgap Fibers(PBGF) and the other is built by splicing a section of HOF between two Large Mode Area-Photonic Crystal Fibers(LMA-PCF). To minimize the splice losses, we carefully optimized the heating time and arc current of the splicer so as not to collapse the air holes of the fiber. It is found that the first interferometer has a temperature sensitivity of 15.4 pm/$^{\circ}C$ and a strain sensitivity of 0.24 pm/${\mu}\varepsilon$. The other interferometer exhibits a temperature sensitivity of 17.4 pm/$^{\circ}C$ and a strain sensitivity of 0.2 pm/${\mu}\varepsilon$.