• 한국결정성장학회지
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• 제13권4호
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• pp.153-156
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• 2003

Pure and Ethylenediaminetetraacetic acid (EDTA) doped L-arginine phosphate (LAP) single crystals were grown from the aqueous solution by temperature lowering method. The effect of EDTA additive on the solubility and metastable zone width of LAP solution has been investigated. Addition of EDTA has enhanced the metastable zone width of LAP and hence bulk crystals could be grown. The growth rate along the [100] direction increases with EDTA additive. Powder X-ray diffraction and FTIR studies reveal the absence of EDTA in the lattice of LAP, This reveals that the addition of EDTA to LAP doesn't influence the crystallinity. However, the transmittance and NLO properties significantly increase with EDTA additive and hence bulk LAP crystals are useful for laser fusion experiments.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.77-78
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• 2007

In this paper, we suppose that the 1-dimensional photonic crystal using holography lithography. We used Ag doped amorphous AsGeSeS which belongs in the chalcogenide materials have sensitive photoluminescence property. The purpose of this experiment is the process to complete 3-D photonic crystal after making 2-D photonic crystal. The lattice formation was made an observation by irradiating He-Ne laser with the AsGeSeS film leaned obliquely. Then, by measuring formed diffraction beam, the diffraction lattice was calculated.

• Transactions on Electrical and Electronic Materials
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• 제16권2호
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• pp.70-73
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• 2015

Many studies have used chemical vapor deposition (CVD) to grow graphene. However, CVD is inefficient in terms of production costs, and inefficient for mass production because a transfer process using a catalytic metal is needed. In this study, graphene thin films were grown on single crystal sapphire substrates without a catalytic metal, using pulsed laser deposition (PLD) to resolve these problems. In addition, the growth of graphene using PLD was confirmed to have a close relationship with the substrate temperature.

• 한국응용과학기술학회지
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• 제19권3호
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• pp.245-249
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• 2002

A (disk-like liquid crystal (DLC) monomer/liquid crystals(LCs)/chiral dopant/dichroic dye) composite was irradiated with ultraviolet (UV) light. The (DLC network/LCs/chiral dopant/dichroic dye) was formed in the homeotropically oriented smectic A(SA) phase by the surface orientation treatment and the electric field. A focal-conic texture exhibiting strong light scattering appeared in the heat-induced chiral nematic phase(N${\ast}$) of the composite upon heating. Thermo-recording in the composite system has been realized by using a He-Ne laser. The laser irradiation was induced the phase transitions from SA phase to chiral nematic(N${\ast}$) phase in the composite system.

• 한국전기전자재료학회논문지
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• 제17권12호
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• pp.1271-1276
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• 2004

Two-dimensionally arrayed nanocolumn lattices were fabricated by using double-exposure laser holographic method. The hexagonal lattice was formed by rotating the sample with 60 degree while the square lattice by 90 degree before the second laser-exposure. The reactive ion etching for a typical time of 30 min using CH$_4$/H$_2$ plasma enhanced the aspect-ratio by more than 1.5 with a slight increase of the bottom width of columns. The etch-damage was observed by photoluminescence (PL) spectroscopy which was removed by the wet chemical etching using HBr/$H_2O$$_2$/$H_2O$ solution, leading into the enhanced PL intensities of the PCs.

• Journal of the Optical Society of Korea
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• 제20권5호
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• pp.593-600
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• 2016

Operation properties, such as output power, beam radius, and crystal temperature rise were investigated in a diode-pumped edge-cooled monolithic Yb:YAG laser with ~ 4 W pumping level. The output power showed saturation behavior because of severe temperature rise and poor spatial overlapping between pump beam and lasing mode. Face cooling geometry by using a sapphire plate was also investigated. No apparent saturation behavior in output power was observed due to the reduced temperature rise, which could be attributed to efficient heat removal through the crystal-sapphire interface.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1998년도 PROCEEDINGS OF THE 14TH KACG TECHNICAL MEETING AND THE 5TH KOREA-JAPAN EMGS (ELECTRONIC MATERIALS GROWTH SYMPOSIUM)
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• pp.19-22
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• 1998

In this work, nonlinear crystals are investigated as investigated ad future diode pumped host laser materials in the green. Optical properties( absorption, emission, secind harmonic generation, and continuous wave lader oscillation in the green) of the most relevant neodymium activeated oxide lader crystals{{{{ ({LiNbO }_{ 3}:MgO, YAI({BO }_{3})_{4} and {LaBGeO }_{ 5})}}}} are investigated and compared under similar experimental conditions

• 한국결정성장학회지
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• 제7권3호
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• pp.465-472
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• 1997

본 연구는 전기 장에서 광여기 탈착과 이온화에 근거한 표면연구의 새로운 장치를 개발하고 시험한 결과를 보고한다. 실험장치의 분해능을 테스트 하기 위해 텡스텐(110)면에서 흡착기체 $H_2$ 와 He 가스를 조사하였으며, 팁의 온도는 80 K이었다. 장세기가 10 V/nm에서 50 V/nm사이에서 사용한 파장은 193 nm이였으며, 텡스텐(110)면에 가스가 흡착되었을때 레이저빔의 전자적인 여기로 부터 흡착가스와 팁에서 여러종류의 이온들이 형성되었다($H_2^+, CO^+, H_2O^+, He^+, W^{3+}$ 그리고 $W^{2+}$). 전체 mass spectrum의 기록은 Transient recorder가 가능하게 한다.

• 한국결정성장학회지
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• 제9권2호
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• pp.173-179
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• 1999

본 연구에서는 비정질 규소 박막의 결정화를 촉진시키기 위하여 표면 활성화 처리의 영향을 관찰하였다. 표면 활성화 방법으로는 습식 연마법(Wet Blasting)과 Nd:YAG 레이저의 빔을 사용하였고, 700~$800^{\circ}C$에서 관상로 열처리를 행하여 고살 결정화에 미치는 영향을 보았다. 결정화 정도의 기준으로는 XRD 분석을 통해 얻은 (111) 피크강도를 이용하였으며, 결정의 품질을 분석하기 위해 Raman 분석을 행하였다. 결정화의 표면 형상에 대한 관찰은 주사전자 현미경(SEM)을 사용하였다. 본 실험 결과 표면 활성화 처리는 비정질 규소박막의 결정화를 촉진하고, 결정의 품질을 향상시키는 것으로 확인되었다. 습식 연마법(Wet Blasting)의 경루 2 Kgf/$\textrm{cm}^2$의 압력이 가장 효과적이었고, 레이저의 에너지는 100~200mJ/$\textrm{cm}^2$가 효과적이었다. 이것은 표면활성화처리를 통하여 비정질 실리콘 박막의 표면에 strain energy가 형성되어 결정화에 필요한 엔탈피에 영향을 미친 효과 때문으로 예상된다.

• Journal of the Optical Society of Korea
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• 제19권4호
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• pp.346-350
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• 2015

We report a measurement of the effective refractive index of a nematic liquid crystal (NLC) inside a Fabry-Perot (FP) etalon according to the applied electric fields. The effective refractive index of the NLC depends on the intensity of the applied electric field. A wavelength-swept laser with a polygon-scanner-based wavelength filter is used as a wide-band optical source to measure the effective refractive index of the NLC. The bandwidth of the optical source is greater than 90 nm around 1300 nm. The fabricated NLC FP etalon consists of glass substrates, gold layers as the electrodes with highly reflective surfaces, polyimide layers as the planar alignment layers, and an LC layer. Furthermore, we measured the Freedericksz transition voltages for three types of NLC FP etalons having thicknesses of $30.6{\mu}m$, $55.4{\mu}m$, and $108.8{\mu}m$. The Freedericksz transition voltages in the three cases are nearly equal. The measured effective refractive indices in the three cases decreased from 1.67 to 1.51 as the applied electric field intensity was increased. Beyond the threshold electric field, the effective refractive indices quickly decreased and eventually saturated at a value of 1.51 for all cases.