Browsing by Author "Yang, T.-J."

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Microwave surface impedance of a nearly ferroelectric superconductor
(2007)
Wu, C.-J.
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Fu, C.-M.
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Kuo, W.-K.
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Yang, T.-J.
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電子物理學系
The intrinsic microwave surface impedance for a nearly ferroelectric superconducting film of finite thickness in the dielectric-like response is theoretically investigated. It is based on the electrodynamics of a nearly ferroelectric superconductor that incorporates the Maxwell's equations, the lattice equations for an ionic lattice, and the superconducting London equation as well. It is found that the surface resistance will be enhanced with decreasing the film thickness when the thickness is less than the London penetration depth. However it will begin to resonate as a function of film thickness at the thickness being more than one London penetration depth. The anomalous resonance peaks occur when the thickness equals the even multiple of the London penetration depth. In the frequency-dependent surface resistance, the number of the resonance peaks is strongly dependent on the film thickness, increasing with increasing the thickness. In addition, peaks are not regularly spaced at a fixed interval. Discussion on this anomaly in the surface resistance will be given.
The optical properties between an incident wave and the active layer of a bubble-pit AgOx-type super-resolution near-field structure
(2007-11-01)
Chau, Y.-F.
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Sun, Y.-S.
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Tsai, D. P.
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Yang, T.-J.
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電子物理學系
The deformation and plasmon effects of collective localized surface plasmons between incident light and bubble-pit AgOx-type super-RENS structure have been studied using finite-difference time-domain (FDTD) method. We find that the polarization, wavelength of incident light, and particle sizes of Ag nanoparticles are sensitive to the plasma resonance. The Ag nanoparticles inside the bubble-pit AgOx-type super-RENS structure give the additional outer boundaries to the motion of the Ag nanoparticles, and excite more evanescent field which located in the far edge of the bubble from the optical axis of the incident beam. The optical properties between active layer and incident light with polarization direction, different wavelengths, and varied particle sizes of Ag nanoparticles exhibits nonlinear optical behavior in the near field. The far-field signals of different wavelength of incident light confirm the relation between highly localized near-field distributions and enhanced resolution of far-field signals. The subwavelength recording marks smaller than the diffraction limit were distinguishable since the Ag nanoparticles with high localized fields transferred evanescent waves to detectable signals in the far field.