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You searched for +publisher:"NSYSU" +contributor:("Chia-Chen Hsu"). Showing records 1 – 3 of 3 total matches.

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NSYSU

1. Tsai, Cheng-Nan. Study of enhancement of Cr4+ concentration in Y3Al5O12 crystal fiber using pre-growth perimeter deposition.

Degree: PhD, Electro-Optical Engineering, 2008, NSYSU

Cr4+ doped Yttrium aluminum garnet (YAG) has a strong spontaneous emission that can generate near-infrared emission from 1.2 to 1.6 μm. This broadband emission have aroused great interest in developing tunable wavelength lasers and amplified spontaneous emitter (ASE).In this dissertation, The valence states of Cr ions in Ca or Ca/Mg co-doped Cr:YAG single-crystal fibers are studied. The fibers were grown using the laser-heated pedestal growth (LHPG) method, followed by annealing treatments up to 1500 °C. The concentrations of the Cr3+ and Cr4+ ions in octahedral and tetrahedral sites in oxygen or nitrogen environments were characterized for the first time to our knowledge. Above 700 °C, migration of Cr4+ between octahedral and tetrahedral sites takes place, the ratio is about 4%; its relative stabilization energy was estimated. For Ca,Cr:YAG annealed in an oxygen or nitrogen environment, it was 0.25 and 0.3 eV, respectively. For Mg,Ca,Cr:YAG annealed in oxygen or nitrogen, it was 0.47 and 0.49 eV, respectively. For the Ca,Cr:YAG crystal fiber (Ca/Cr=113.1%) with oxygen annealing, about 35% and 2.5% of Ca ions took part in charge compensation for Cr4+ in the octahedral and tetrahedral sites, respectively. The density of oxygen vacancies depends on the concentration of Ca ions. The estimated ratios of the unreacted oxygen vacancies to total oxygen vacancies were about 63% and 88% for oxygen and nitrogen annealing, respectively. The main limitation on the concentration of Cr4+ in the tetrahedral site of YAG is the presence of unreacted oxygen vacancies. Furthermore, chromium ions tend to diffuse outward during the LHPG of YAG crystal fiber, in which the average Cr4+ ion concentration decreases significantly after each diameter-reduction step. The Cr4+ ions are replenished using an electron gun to deposit Cr2O3 and divalent-ion oxide (CaO or MgO) on the source rod circumference before growth. It was observed that Ca2+ has better efficiency to diffuse into the source rod more efficiently than Mg2+generating fewer defects and stacking faults. By CaO deposition and post growth annealing at 1350 °C under an oxygen environment, a 110% increase in Cr4+ concentration was obtained. The achieved Cr4+ concentration and the ratio of Cr4+ to total Cr were 1.76 1018 cm-3 and 5.5, respectively. Advisors/Committee Members: Yi-Jen Chiu (chair), Ying-Chien Tsai (chair), Chia-Chen Hsu (chair), Tsong-Sheng Lay (chair), Wood-Hi Cheng (chair), Sheng-Lung Huang (committee member), Chao-Kuei Lee (chair), Pochi Yeh (chair).

Subjects/Keywords: Cr4+:YAG; crystal fiber; laser-heated pedestal growth

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APA (6th Edition):

Tsai, C. (2008). Study of enhancement of Cr4+ concentration in Y3Al5O12 crystal fiber using pre-growth perimeter deposition. (Doctoral Dissertation). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0723108-162918

Chicago Manual of Style (16th Edition):

Tsai, Cheng-Nan. “Study of enhancement of Cr4+ concentration in Y3Al5O12 crystal fiber using pre-growth perimeter deposition.” 2008. Doctoral Dissertation, NSYSU. Accessed October 23, 2019. http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0723108-162918.

MLA Handbook (7th Edition):

Tsai, Cheng-Nan. “Study of enhancement of Cr4+ concentration in Y3Al5O12 crystal fiber using pre-growth perimeter deposition.” 2008. Web. 23 Oct 2019.

Vancouver:

Tsai C. Study of enhancement of Cr4+ concentration in Y3Al5O12 crystal fiber using pre-growth perimeter deposition. [Internet] [Doctoral dissertation]. NSYSU; 2008. [cited 2019 Oct 23]. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0723108-162918.

Council of Science Editors:

Tsai C. Study of enhancement of Cr4+ concentration in Y3Al5O12 crystal fiber using pre-growth perimeter deposition. [Doctoral Dissertation]. NSYSU; 2008. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0723108-162918


NSYSU

2. Hung, Wen-chi. A Study of Surface Plasmon Effect Excited on Metal Nanoparticles.

Degree: PhD, Electro-Optical Engineering, 2008, NSYSU

Collective oscillation of conduction electrons in metallic nanoparticles known as localized surface plasmon resonance has been studied for nano-optics applications. The excitation of localized surface plasmons on nano-structured metal material leads to strong light scattering and absorption. Since the localized surface plasmon resonance is strongly dependent on the shape, size, size distribution, and dielectric property of surrounding environment of nano-structured metal, the dependence can be applied in wide applications. However, the direct and non-destructed observation of nano-structured metal is required to the development of nano-technology, we proposed a real time optical observation due to the optical respons of metal nano-particles system. Furthermore, we proposed a fast and simple method to fabricate a high order metal nano-particles array and used liquid crystal material to directly modulate the surface plasmon effect on the metal nanoparticles. The purpose of this work is to study the surface plasmon effect excited on metal nanoparticles. These works are described as follows: A. The topic of the first work is âReal time absorbance spectra due to optical dynamics of silver nano-particles filmâ, we report the real time absorbance spectra due to optical dynamics of silver nano-particles film under a heating treatment from 28 to 300 â. A 7nm-thicked sliver film was thermally deposited on an indium tin oxide glass substrate. In the process of heating, the real time absorbance spectra of silver nano-particles film were measured by an optical spectrometer. It was noted that the absorbance spectra of the film varied with the heat-treating temperature and time. The peak position in the spectra curve shifted to shorter wavelength below the temperature of 250 â, then shifted to red band due to higher temperature treatment. With the comparison of scanning electron micrograph analysis, the real time absorbance spectra exhibited a particular optical property confirmed by the dynamic dark-field optical microscopy system. The real-time absorbance spectra and dark-field micrographs analyses lead to a direct and non-destructed observation of growing evolution of metal nano-particles. B. The topic of the second work is âLaser pulse induced gold nanoparticles gratingâ. We report the results of our experimental investigation of laser induced gold nano-particle gratings and their optical diffraction properties. A single shot of a pair of Nd-YAG laser pulses of the same polarization is directed toward a thin gold film of thickness 6 nm on a substrate of polymethyl methacrylate (PMMA). As a result of the laser illumination, the thin gold film is fragmented into an array of nano-particles. Using scanning electron and dark-field optical micrographs, we discovered that the morphology of the gold nanoparticles grating is dependent on the fluence of laser pulse. The spectrum of first order diffraction shows a spectral dependence, possibly due to the presence of the nano-particles of various sizes. The ablation of thin films of… Advisors/Committee Members: Ming-Shan Tsai (committee member), I-Min Jiang (chair), Andy Ying-Guey, Fuh (chair), Sheng-Lung Huang (chair), Tsong-Sheng Lay (chair), Chia-Chen Hsu (chair), Pochi Yeh (chair), Wood-Hi Cheng (committee member), Tsung-Hsien Lin (chair).

Subjects/Keywords: metal nanoparticle; surface plasmon; liquid crystals

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APA (6th Edition):

Hung, W. (2008). A Study of Surface Plasmon Effect Excited on Metal Nanoparticles. (Doctoral Dissertation). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0725108-173639

Chicago Manual of Style (16th Edition):

Hung, Wen-chi. “A Study of Surface Plasmon Effect Excited on Metal Nanoparticles.” 2008. Doctoral Dissertation, NSYSU. Accessed October 23, 2019. http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0725108-173639.

MLA Handbook (7th Edition):

Hung, Wen-chi. “A Study of Surface Plasmon Effect Excited on Metal Nanoparticles.” 2008. Web. 23 Oct 2019.

Vancouver:

Hung W. A Study of Surface Plasmon Effect Excited on Metal Nanoparticles. [Internet] [Doctoral dissertation]. NSYSU; 2008. [cited 2019 Oct 23]. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0725108-173639.

Council of Science Editors:

Hung W. A Study of Surface Plasmon Effect Excited on Metal Nanoparticles. [Doctoral Dissertation]. NSYSU; 2008. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0725108-173639


NSYSU

3. Tai, Yung-hui. Investigations of Strongly Charge Transfer Molecules Using Nonlinear Optical Scattering and Absorption.

Degree: PhD, Physics, 2005, NSYSU

This thesis provides an extensive study of the first molecular hyperpolarizability b of charge-transfer chromophores using hyper-Rayleigh scattering (HRS). The charge-transfer chromophores used in present work involve the tricyanohydrofuranï¼TCFï¼group as an electron acceptor, and/or thiophene in the pi-electron bridge. TCF is a very strong electron acceptor and thiophene greatly lowers the resonance energy. Their presence significantly increases the beta value of the chromophore, therefore enhancing potentials in applications. In hyper-Rayleigh scattering experiments, the laser radiation with tunable wavelengths is used as an excitation source for measuring the frequency dependence of beta. The experiment shows beta exhibiting a significant dispersion in the two-photon resonance region. Using the linear absorption spectrum in coordination with theory, we show that it is possible to use Kramers-Kronig (K-K) transform to reproduce the experimental beta value in the two-photon resonance region. The K-K approach provides an extension to the conventional Oudar-Chemla equation, which is invalid in the spectral region in which two-photon resonance occurs. Using the new approach, it is shown that reliable values of intrinsic hyperpolarizabilities beta_zero of charge-transfer chromophores can be extracted. The coordination of beta_zero with molecular structure provides one with an insight for the origin of the enhancement of the first molecular hyperpolarizability of charge-transfer chromophores. This thesis examines the variation of beta_zero with molecular structure. The same technique is also applied to a dendrimer that has charge-transfer nonlinear optical chromophores incorporated in the dendritic structure. The measured frequency dependent hyperpolarizability of the dendrimer is compared with that calculated from the linear absorption spectrum by the KK transform technique. The intrinsic hyperpolarizability beta_zero of the dendrimer obtained is compared with that of the single chromophore having a structure similar to that incorporated in the dendrimer. The comparison shows that the 3D dendritic structure is effective in reducing the interaction between chromophores by providing sufficient space between them, hence avoiding the possibility of aggregation formation due to attractive interactions between chromophores. The topic of two-photon fluorescence (TPF), which is related to HRS, is also investigated. The intensity of TPF is generally proportional to the square of the incident excitation intensity. Careful measurements of the TPF intensity of a nonlinear optical chromophore in conjunction with required auxiliary parameters have been used as a technique for determining the two-photon absorption cross-section. The TPF intensity measurement carried out in this thesis uses a variety of intensities. At low intensity excitation, the TPF intensity follows the usual quadratic intensity law (QIL), whereas deviations from the QIL are observed at higher incident intensities. The observation of similar lineshape associated… Advisors/Committee Members: Jui-hung Hsu (chair), Ting-chang Chang (chair), I-min Jiang (chair), Sheng-lung Huang (chair), Chia-chen Hsu (chair), Li-wei Tu (chair), Jennshyong Hwang (chair), Chin-hsien Wang (committee member).

Subjects/Keywords: Second harmonic generation; First molecule hyperpolarizability; Charge-transfer chromophore; Two-photon absorption cross section; Nonlinear optics; Optical poling; Two-photon fluorescence; Hyper-Rayleigh scattering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Tai, Y. (2005). Investigations of Strongly Charge Transfer Molecules Using Nonlinear Optical Scattering and Absorption. (Doctoral Dissertation). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0119105-131846

Chicago Manual of Style (16th Edition):

Tai, Yung-hui. “Investigations of Strongly Charge Transfer Molecules Using Nonlinear Optical Scattering and Absorption.” 2005. Doctoral Dissertation, NSYSU. Accessed October 23, 2019. http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0119105-131846.

MLA Handbook (7th Edition):

Tai, Yung-hui. “Investigations of Strongly Charge Transfer Molecules Using Nonlinear Optical Scattering and Absorption.” 2005. Web. 23 Oct 2019.

Vancouver:

Tai Y. Investigations of Strongly Charge Transfer Molecules Using Nonlinear Optical Scattering and Absorption. [Internet] [Doctoral dissertation]. NSYSU; 2005. [cited 2019 Oct 23]. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0119105-131846.

Council of Science Editors:

Tai Y. Investigations of Strongly Charge Transfer Molecules Using Nonlinear Optical Scattering and Absorption. [Doctoral Dissertation]. NSYSU; 2005. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0119105-131846

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