Browsing by Author "Wu, Che-Yao"

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One-Dimensional Photonic Crystal Ring Lasers on SiO2 Substrate
(2013)
Lu, Tsan-Wen
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Tsai, Wei-Chi
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Wu, Che-Yao
;
Lee, Po-Tsung
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光電工程學系
One-dimensional photonic crystal ring resonators are utilized in realizing InGaAsP/SiO2 hybrid lasers via adhesive bonding technique. Low threshold single-mode lasing properties are investigated and further altered via inducing a nanocavity.
Plasmonic Coupling in Gold Nanoring Dimers: Observation of Coupled Bonding Mode
(2012-03-01)
Tsai, Chia-Yang
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Lin, Jyun-Wei
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Wu, Che-Yao
;
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.
Slab Thickness Dependence of Localized Surface Plasmon Resonance Behavior in Gold Nanorings
(2013-06-01)
Tsai, Chia-Yang
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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