Browsing by Author "Tsai, Chia-Yang"

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A Novel Hybrid Plasmonic Rod-dimer/Ring Nanostructure for Sensing and Trapping
(2014)
Lin, Jia-Yu
;
Tsai, Chia-Yang
;
Lin, Pin-Tso
;
Hsu, Tse-En
;
Lee, Po-Tsung
We propose and investigate a novel hybrid plasmonic rod-dimer/ring (RDR) nanostructure with significantly enhanced near-field at the gap region for its potential on sensing and trapping applications.
A rate-distortion analysis on motion prediction efficiency and mode decision for scalable wavelet video coding
(2010-11-01)
Tsai, Chia-Yang
;
Hang, Hsueh-Ming
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A rate-distortion model for describing the motion prediction efficiency in interframe wavelet video coding is proposed in this paper. Different from the non-scalable video coding, the scalable wavelet video coding needs to operate under multiple bitrate conditions and it has an open-loop structure. The conventional Lagrangian multiplier, which is widely used to solve the rate-distortion optimization problems in video coding, does not fit well into the scalable wavelet structure. In order to find the rate-distortion trade-off due to different bits allocated to motion and textual information, we suggest a motion information gain (MIG) metric to measure the motion prediction efficiency. Based on this metric, a new cost function for mode decision is proposed. Compared with the conventional Lagrangian method, our experiments show that the proposed method is less extraction-bitrate dependent and generally improves both the PSNR performance and the visual quality for the scalability cases. (c) 2010 Elsevier Inc. All rights reserved.
A rate-distortion analysis on motion prediction efficiency and mode decision for scalable wavelet video coding
(2010-11-01)
Tsai, Chia-Yang
;
Hang, Hsueh-Ming
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A rate-distortion model for describing the motion prediction efficiency in interframe wavelet video coding is proposed in this paper. Different from the non-scalable video coding, the scalable wavelet video coding needs to operate under multiple bitrate conditions and it has an open-loop structure. The conventional Lagrangian multiplier, which is widely used to solve the rate-distortion optimization problems in video coding, does not fit well into the scalable wavelet structure. In order to find the rate-distortion trade-off due to different bits allocated to motion and textual information, we suggest a motion information gain (MIG) metric to measure the motion prediction efficiency. Based on this metric, a new cost function for mode decision is proposed. Compared with the conventional Lagrangian method, our experiments show that the proposed method is less extraction-bitrate dependent and generally improves both the PSNR performance and the visual quality for the scalability cases. (c) 2010 Elsevier Inc. All rights reserved.
High sensitivity plasmonic index sensor using slab-like gold nanoring array
(2011)
Tsai, Chia-Yang
;
Lu, Shao-Ping
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Lin, Jyun-Wei
;
Lee, Po-Tsung
;
光電工程學系
We investigate the index sensing characteristics of plasmonic arrays based on square lattice slab-like gold nanorings with different ring widths. High sensitivity of 691 nm per RIU is obtained for nanorings with 199 nm width. (C) 2010 Optical Society of America
High sensitivity plasmonic index sensor using slablike gold nanoring arrays
(2011-04-11)
Tsai, Chia-Yang
;
Lu, Shao-Ping
;
Lin, Jyun-Wei
;
Lee, Po-Tsung
;
光電工程學系
We investigate the index sensing characteristics of plasmonic arrays based on square lattice slablike gold nanorings (NRs) with different ring widths. The gold NR arrays exhibit two extinction peaks in the visible and near-infrared corresponding to antibonding and bonding modes. Redshift and blueshift in antibonding and bonding modes when broadening the average ring width are observed. We experimentally demonstrate the sensitivity of bonding mode can be tuned by varying the average ring width. High sensitivity of 691 nm per refractive index unit is obtained for NRs with 199 nm average ring width. (C) 2011 American Institute of Physics. [doi:10.1063/1.3579536]
Method and apparatus for interframe wavelet video coding
(2005-09-15)
Tsai, Sam S.
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Hang, Hsueh-Ming
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Tsai, Chia-Yang
;
Chiang, Tihao
The present invention provides a method and apparatus for interframe wavelet video coding which comprises Motion Compensated Temporal Filtering and Discrete Wavelet Transform Coding to obtain: 1. compressed quantification error and scalability on temporal analysis and spatial analysis, and 2. scalability on Motion Information (MI) data so that the performance of wavelet video coding on low bitrate can be improved. A method for partitioned coding on MI is proposed: 1. to partitioned coding a motion vector according to the spatial block, the temporal frame, or the numeric precision; 2. to partition motion vectors to a plurality of layers, and, when the video bitstream changes, only the required MI is put into the final bitstream. Accordingly, the performance of wavelet video compression on low bitrate is greatly improved while the compression rate on high bitrate is only a little lower.
Nanophotonic structures for highly efficient on-chip optical manipulation
(2018-01-01)
Lee, Po-Tsung
;
Lu, Tsan-Wen
;
Lin, Pin-Tso
;
Lin, Chia-Yu
;
Tsai, Chia-Yang
In this report, we introduce our proposed nanophotonic structures for highly efficient optical manipulation, including utilizing photonic crystal waveguides, nanocavities, and metallic structures with localized surface plasmon resonances. Owing to their waveguide-accessible configurations and highly concentrated optical modes with large field gradients beyond the diffraction limit, highly efficient optical trapping can be realized in sub-wavelength scale.
One-Sided rho-GGD Source Modeling and Rate-Distortion Optimization in Scalable Wavelet Video Coder
(2011-11-01)
Tsai, Chia-Yang
;
Hang, Hsueh-Ming
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We develop an accurate source model, one-sided rho-generalized Gaussian distribution (GGD), for approximating the residual signals in scalable wavelet video coding. An efficient piecewise linear expression is suggested to estimate the shape parameter of the one-sided rho-GGD. We also improve the model accuracy in matching the real data by modifying the. parameter estimation formula. Continuing our previous work on developing the motion information gain metric to measure the motion information efficiency, we now incorporate the one-sided rho-GGD model in the cost function, which is used for deciding the motion vectors and motion estimation mode in scalable wavelet video coding. Compared with the conventional Lagrangian optimization, our simulation results show that the new mode decision method generally improves the peak signal-to-noise ratio performance in the combined signal-to-noise ratio and temporal scalability cases.
Optical Properties of Plasmonic Mirror-Image Nanoepsilon
(2016-07-12)
Lin, Jia-Yu
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Tsai, Chia-Yang
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Lin, Pin-Tso
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Hsu, Tse-En
;
Hsiao, Chi-Fan
We propose a novel mirror-image nanoepsilon (MINE) structure to achieve highly localized and enhanced near field at its gap and systematically investigate its plasmonic behaviors. The MINE can be regarded as a combination of two fundamental plasmonic nanostructures: a nanorod dimer and nanoring. By adapting a nanoring surrounding a nanorod dimer structure, the nanorod is regarded as a bridge pulling the charges from the nanoring to the nanorod, which induces stronger plasmon coupling in the gap to boost local near-field enhancement. Two resonance peaks are identified as the symmetric and anti-symmetric modes according to the symmetries of the charge distributions on the ring and rod dimer in the MINE. The symmetric mode in the MINE structure is preferred because its charge distribution leads to stronger near-field enhancement with a concentrated distribution around the gap. In addition, we investigate the influence of geometry on the optical properties of MINE structures by performing experiments and simulations. These results indicate that the MINE possesses highly tunable optical properties and that significant near-field enhancement at the gap region and rod tips can be realized by the gap and lightning-rod effects. The results improve understanding of such complex systems, and it is expected to guide and facilitate the design of optimum MINE structures for various plasmonic applications.
Plasmonic Coupling in Gold Nanoring Dimers: Observation of Coupled Bonding Mode
(2012-03-01)
Tsai, Chia-Yang
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Lin, Jyun-Wei
;
Wu, Che-Yao
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Lin, Pin-Tso
;
Lu, Tsan-Wen
We investigate the optical properties of gold nanoring (NR) dimers in both simulation and experiment. The resonance peak wavelength of gold NR dimers is strongly dependent on the polarization direction and gap distance. As the gold NR particles approach each other, exponential red shift and slight blue shift of coupled bonding (CB) mode in gold NR dimers for longitudinal and transverse polarizations are obtained. In finite element method analysis, a very strong surface plasmon coupling in the gap region of gold NR diners is observed, whose field intensity at the gap distance of 10 nm is enhanced 23% compared to that for gold nanodisk (ND) dimers with the same diameter. In addition, plasmonic dimer system exhibits a great improvement in the sensing performance. Near field coupling in gold NR dimers causes exponential increase in sensitivity to refractive index of surrounding medium with decreasing the gap distance. Compared with coupled dipole mode in gold ND diners, CB mode in gold NR dimers shows higher index sensitivity. This better index sensing performance is resulted form the additional electric field in inside region of NR and the larger field enhancement in the gap region owing to the stronger coupling of collective dipole plasmon resonances for CB mode. These results pave the way to design plasmonic nanostructures for practical applications that require coupled metallic nanopartides with enhanced electric fields.
Plasmonic Properties and Biosensing of Gold Elliptical Nanoring Arrays
(2013)
Tsai, Chia-Yang
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Chang, Kai-Hao
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Wu, Che-Yao
;
Lee, Po-Tsung
;
光電工程學系
We investigate the optical properties and biosensing of gold elliptical nanoring (ENR) arrays with various aspect ratios. Gold ENRs with 1.58 high aspect ratio show a total wavelength shift of 35 nm for molecule sensing.
RATE-DISTORTION MODEL FOR MOTION PREDICTION EFFICIENCY IN SCALABLE WAVELET VIDEO CODING
(2009)
Tsai, Chia-Yang
;
Hang, Hsueh-Ming
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A rate-distortion model for motion prediction efficiency in scalable wavelet video coding is proposed in this paper. The Lagrangian multiplier is widely used to solve the rate-distortion optimization problems in video coding, especially on mode decision and rate-constrained motion estimation. Different from the non-scalable video coding, the scalable wavelet video coding needs to operate under multiple bitrate conditions and it has an open-loop structure. Therefore, the conventional rate-distortion optimization technique is not suitable for the scalable wavelet case. By analyzing the rate-distortion trade-off due to different bits allocated to motion information, we propose a motion prediction gain (MPG) metric to measure motion coding efficiency. Based on the MPG metric, a new cost function for mode decision is thus proposed. Compared with the conventional Lagrangian multiplier optimization method, our experiments show that the new mode decision procedure can generally improve the PSNR performance for, particularly, the combined SNR and temporal scalability.
rho-GGD SOURCE MODELING FOR WAVELET COEFFICIENTS IN IMAGE/VIDEO CODING
(2008)
Tsai, Chia-Yang
;
Hang, Hsueh-Ming
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A rho-GGD source model is proposed in this paper. The probability distribution of wavelet coefficients has been previously modeled as Laplacian or generalized Gaussian distribution (GGD). The Laplacian model is simple in calculation but not accurate; on the other hand, GGD is accurate but requires a very complicated modeling procedure. In this paper, we introduce a new parameter rho into the GGD source model, where rho is the probability of zero-value coefficients. The shape parameter of the GGD model can then be easily estimated from rho and the standard deviation. Moreover, a piecewise linear approximation method is proposed to further reduce complexity. Our experiments show that the rho-GGD model has high accuracy and consistent performance for modeling the wavelet coefficient pdfs for both spatial 2-D DWT and interframe wavelet video cases.
Slab Thickness Dependence of Localized Surface Plasmon Resonance Behavior in Gold Nanorings
(2013-06-01)
Tsai, Chia-Yang
;
Wu, Che-Yao
;
Chang, Kai-Hau
;
Lee, Po-Tsung
;
光電工程學系
We present detailed experimental and numerical studies of plasmonic properties of gold nanoring (NR) arrays with different slab thicknesses from 15 to 125 nm. The hybrid plasmon resonances for the bonding and antibonding modes in gold NRs exhibit a high slab thickness dependence behavior in optical properties. For the thinner slab thickness below 50 nm, both hybrid modes show large spectral tunabilities by varying the slab thickness. Furthermore, for such hollow NR structure, the enhancements of electric field intensities at the inner and outer ring surfaces when reducing the slab thickness are investigated. We observe a significant transition of field distributions for the antibonding mode. All these features can be understood by surface charge distributions from our simulations. The results of this study offer a potential strategy to design a composite plasmonic nanostructure with large field enhancement for numerous applications.
The aspect ratio effect on plasmonic properties and biosensing of bonding mode in gold elliptical nanoring arrays
(2013-06-17)
Tsai, Chia-Yang
;
Chang, Kai-Hao
;
Wu, Che-Yao
;
Lee, Po-Tsung
;
光電工程學系
We investigate both numerically and experimentally the optical properties and biosensing of gold elliptical nanoring (ENR) arrays with various aspect ratios. The gold ENR exhibits a strong localized surface plasmon bonding mode in near-infrared region, whose peak wavelength is red-shifted as increasing the aspect ratio under longitudinal and transverse polarizations. Furthermore, the disk- and hole-like optical properties for longitudinal and transverse modes are observed, which cause different behaviors in field intensity enhancement. For biomolecule sensing, we find that both modes show increased surface sensitivities when enlarging the aspect ratio of gold ENR. (C) 2013 Optical Society of America