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Optical Waveguide Formed in a LiTaO3 Crystal by Using MeV C3+ Ion Implantation
Gang Fu,Xue-Lin Wang 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.4
Planar waveguides were formed in LiTaO3 crystals by using 6.0-MeV C3+-ion implantation at room temperature. The prism-coupling method was used to take dark mode measurements at both 633 nm and 1539 nm. The reflectivity calculation method was used to reconstruct the refractive index profile in the waveguide. TRIM’98 (Transport of Ions in Matter) was also used to simulate the damage distribution in the LiTaO3. Barrier-confined waveguides were found to be formed in LiTaO3. Possible reasons for the different refractive-index profiles in the LiTaO3 and the LiNbO3waveguides are discussed.
1.54 μm photoluminescence emission at room-temperature of erbium-implanted lithium niobate crystal
Gang Fu,Shi Ling Li,Xue Lin Wang,Feng Chen,Ke Ming Wang 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.-
Erbium doped materials are of great interest in integrated optoelectronic technology, due to their Er³+ intra-4f emission at 1.54 μm, a standard telecommunication wavelength. Lithium niobate crystals (LN) are of great importance for fabrication of integrated optical devices, due to their excellent properties such as high electro-optical coefficient, low propagation loss, and high Curie temperature. Lithium niobate crystal has been implanted with 500 keV Er ions at a fluence of 3.0×10 15 ions/㎝² with the aim of optically doping the material in the near surface region. In order to recrystallize the amorphized implanted region the sample was annealed at 500℃ for 90 min in oxygen atmosphere. Photoluminescence (PL) and Rutherford backscattering spectrometry studies were performed on the as-implanted sample before and after annealing. 1.54 μm room-temperature photoluminescence emission was observed in the annealed sample. The relationship between annealing temperature and photoluminescence intensity is discussed.
Diisocyanate 및 Chain Extender의 화학적 구조가 폴리우레탄의 열적 특성에 미치는 영향
박기호,김광복,이한섭,Park, Ki-Ho,Jin, Gangfu,Lee, Han-Sup 한국섬유공학회 2008 한국섬유공학회지 Vol.45 No.2
Polyurethane(PU), a type of thermoplastic elastomer, consists of two different segments (hard and soft segments) that are incompatible at room temperature. Depending on the chemical and physical structure of those two segments, polyurethane shows various internal structures. In this study, a series of polyurethane were synthesized using PPDI (l,4-phenylene diisocyanate), TODI(3,3'-dimethyl diphenyl 4,4'-diisocyanate), MDI(4,4'-diphenylmethane diisocyanate) as disocyanate, 1,4 BD and HQEE(hydroxyquinone-di-(beta-hydroxyethyl)ether) as chain extender in order to test the effect of chemical structure of hard segment on the phase separation behavior and thermal stability of polyurethane. The effect of diisocyanate and chain extender on the thermal stability of polyurethane was measured with DSC, POM, SAXS and FTIR methods. Compared with PU based on the asymmetric and aliphatic component, PUs based on the symmetric and aromatic chemical structures were found to form phase separated structure showing enhanced thermal stability. The good thermal properties were also explained in terms of the good packing behavior between hard segments in the PPDI-based polyurethane.