Browsing by Author "Lee, C. C."

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Exploiting a monolithic passively Q-switched Nd:YAG laser to mimic a single neuron cell under periodic stimulation
(2020-07-15)
Chen, Y. F.
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Lee, C. C.
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Hsiao, J. Q.
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Huang, H. Y.
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Tsou, C. H.
A monolithic passively Q-switched Nd:YAG laser under periodic pulse pumping is originally exploited to emulate the response of a single neuron cell stimulated by periodic pulse inputs. Experimental results reveal that the output characteristics of the monolithic passively Q-switched laser can analogously manifest not only the firing patterns but also the frequency-locked plateaus of the single neuron cell. Moreover, the sine circle map is innovatively used to generate the output pulse sequences that can exactly correspond to experimental firing patterns. The present exploration indicates that a monolithic passively Q-switched solid-state laser is highly feasible to be developed as a compact artificial neuron cell. (C) 2020 Optical Society of America
Ordered YBCO sub-micron array structures induced by pulsed femtosecond laser irradiation
(2008-12-08)
Luo, C. W.
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Lee, C. C.
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Li, C. H.
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Shih, H. C.
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Chen, Y. -J.
We report on the formation of organized sub-micron YBa(2)Cu(3)O(7) (YBCO) dots induced by irradiating femtosecond laser pulses on YBCO films prepared by pulse laser deposition with fluence in the range of 0.21 similar to 0.53 J/cm(2). The morphology of the YBCO film surface depends strongly on the laser fluences irradiated. At lower laser fluence (similar to 0.21 J/cm(2)) the morphology was pattern of periodic ripples with sub-micrometer spacing. Slightly increasing the laser fluence to 0.26 J/cm(2) changes the pattern into organized sub-micron dots with diameters ranging from 100 nm to 800 nm and height of 150 nm. Further increase of the laser fluence to over 0.32 J/cm(2), however, appeared to result in massive melting and led to irregular morphology. The mechanism and the implications of the current findings will be discussed. Arrays of YBCO sub-micron dots with T(c) = 89.7 K were obtained. (C) 2008 Optical Society of America
Stress singularities in an anisotropic body of revolution
(2014-05-15)
Huang, C. S.
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Hu, C. N.
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Lee, C. C.
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Chang, M. J.
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土木工程學系
To fill the gap in the literature on the application of three-dimensional elasticity theory to geometrically induced stress singularities, this work develops asymptotic solutions for Williams-type stress singularities in bodies of revolution that are made of rectilinearly anisotropic materials. The Cartesian coordinate system used to describe the material properties differs from the coordinate system used to describe the geometry of a body of revolution, so the problems under consideration are very complicated. The eigenfunction expansion approach is combined with a power series solution technique to find the asymptotic solutions by directly solving the three-dimensional equilibrium equations in terms of the displacement components. The correctness of the proposed solution is verified by convergence studies and by comparisons with results obtained using closed-form characteristic equations for an isotropic body of revolution and using the commercial finite element program ABAQUS for orthotropic bodies of revolution. Thereafter, the solution is employed to comprehensively examine the singularities of bodies of revolution with different geometries, made of a single material or bi-materials, under different boundary conditions. (C) 2014 Elsevier Ltd. All rights reserved.
Superconducting to spin-glass state transformation in beta-pyrochlore K(x)Os(2)O(6)
(2011-03-14)
Lee, C. C.
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Lee, W. L.
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Lin, J. -Y.
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Tsuei, C. C.
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Lin, J. G.
beta-pyrochore KOs(2)O(6), which shows superconductivity below similar to 9.7 K, has been converted into K(x)Os(2)O(6) (x less than or similar to 2/3-1/2) electrochemically to show spin-glass-like behavior below similar to 6.1 K. A room-temperature sample surface potential versus charge transfer scan indicates that there are at least two two-phase regions for x between 1 and 0.5. A rattling model of superconductivity for the title compound has been examined using electrochemical potassium de-intercalation. The significant reduction of superconducting volume fraction due to minor potassium reduction suggests the importance of defect and phase coherence in the rattling model. Magnetic susceptibility, resistivity, and specific heat measurement results have been compared between the superconducting and spin-glass-like samples.
Superconducting to spin-glass state transformation in beta-pyrochlore KxOs2O6
(2011-03-14)
Lee, C. C.
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Lee, W. L.
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Lin, J. -Y.
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Tsuei, C. C.
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Lin, J. G.
beta-pyrochore KOs2O6, which shows superconductivity below similar to 9.7 K, has been converted into KxOs2O6 (x less than or similar to 2/3-1/2) electrochemically to show spin-glass-like behavior below similar to 6.1 K. A room-temperature sample surface potential versus charge transfer scan indicates that there are at least two two-phase regions for x between 1 and 0.5. A rattling model of superconductivity for the title compound has been examined using electrochemical potassium de-intercalation. The significant reduction of superconducting volume fraction due to minor potassium reduction suggests the importance of defect and phase coherence in the rattling model. Magnetic susceptibility, resistivity, and specific heat measurement results have been compared between the superconducting and spin-glass-like samples.
Timing jitter reduction of passively Q-switched solid-state lasers by coupling resonance between pumping and firing rates
(2020-05-15)
Chen, Y. F.
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Chien, P. Y.
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Lee, C. C.
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Huang, K. F.
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Liang, H. C.
The coupling resonance between pumping and firing rates is originally proposed to achieve the timing jitter reduction of a Nd : YVO4 laser passively Q-switched with a saturable absorber. When the pumping rate is higher than the spontaneous emission rate, it is experimentally confirmed that the pulse firing rate can be fractionally locked with the pumping rate by controlling the pump power. The locking characteristics of the firing rate display a variety of complex plateaus that can be excellently manifested with the sine-circle map. From numerical analyses, the coupling strength can be verified to be effectively enhanced by reducing the duty cycle of the pumping rate. (C) 2020 Optical Society of America