Browsing by Author "Yang, Zih-Ying"

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Effective Absorption Enhancement in Dielectric Slab with Embedded Single-Strip and Paired-Strips Gold Nanoantennas
(2013-01-01)
Yang, Zih-Ying
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Chen, Kuo-Ping
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照明與能源光電研究所
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光電工程學系
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Institute of Lighting and Energy Photonics
The finite element method (FEM) is used to investigate the near-field enhancement of gold paired-strips nanoantennas. The integral enhanced localized field within 100nm thin slab is 2.4 times larger than single-strip gratings.
Effective absorption enhancement in dielectric thin-films with embedded paired-strips gold nanoantennas
(2014-06-02)
Yang, Zih-Ying
;
Chen, Kuo-Ping
;
照明與能源光電研究所
;
影像與生醫光電研究所
;
Institute of Lighting and Energy Photonics
This study focuses on determining the optimized thickness of an absorbing thin-film with embedded gold nanoantennas, for absorption enhancement. Gold paired-strips nanoantennas with small gaps have been proposed for light trapping because of the high localized electric field in the gap due to resonance. Paired-strips nanoantennas with small gaps produce higher effective absorption compared to single-strip gratings. From the average absorption two-dimensional map, the absorption enhancement may increase by a factor of up to 20 for gold paired-strips nanoantennas embedded in a 100 nm thick P3HT:PCBM thin-film. (C) 2014 Optical Society of America
Narrow-Band Thermal Emitter with Titanium Nitride Thin Film Demonstrating High Temperature Stability
(1970-01-01)
Yang, Zih-Ying
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Ishii, Satoshi
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Doan, Anh Tung
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Shinde, Satish Laxman
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Dao, Thang Duy
A refractory wavelength selective thermal emitter is experimentally realized by the excitation of Tamm plasmon polaritons (TPPs) between a titanium nitride (TiN) thin film and a distributed Bragg reflector (DBR). The absorptance reaches nearly unity at approximate to 3.73 mu m with the bandwidth of 0.36 mu m in the experiment. High temperature stabilities are confirmed up to 500 and 1000 degrees C in ambient and in vacuum, respectively. When the TiN TPP structure is compared to the TiN-insulator-TiN (TiN-metal-insulator-metal (MIM)) structure, the former shows higher Q-factor, which indicates the advantage of choosing the TiN TTP structure against the MIM structure. The proposed refractory TiN TPP structure is lithography-free and scalable, which paves a way for large scale thermal emitters in practical usage.
Narrowband Wavelength Selective Thermal Emitters by Confined Tamm Plasmon Polaritons
(2017-09-01)
Yang, Zih-Ying
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Ishii, Satoshi
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Yokoyama, Takahiro
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Thang Duy Dao
;
Sun, Mao-Guo
This study experimentally demonstrates infrared wavelength selective thermal emission based on Tamm plasmon polaritons (TPPs). Unlike conventional TPP structures, which have a thin metal layer on a distributed Bragg reflector (DBR), the proposed structure has a thick metal under a DBR that is more robust for thermal radiation. The number of DBR pairs is a critical factor in maximizing the narrowband emission needed to satisfy the impedance matching condition, which varies with the choice of metal film. Optimum designs for four different metals, aluminum, gold, molybdenum, and tungsten, are presented. The temporal coupled-mode theory was introduced to explain the origin of the high Q-factor of the proposed structure, which can achieve a twice higher Q factor for the measured emissivity compared to typical plasmonic thermal emitters. The structure is one-dimensional, consisting of only multilayers and free from nanopatterning, offering a practical design in applications such as gas sensing, narrowband IR sources, and thermophotovoltaics.
Nonradiating Silicon Nanoantenna Metasurfaces as Narrowband Absorbers
(2018-07-01)
Yang, Chi-Yin
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Yang, Jhen-Hong
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Yang, Zih-Ying
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Zhou, Zhong-Xing
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Sun, Mao-Guo
High-refractive-index (HRI) nanostructures support optically induced electric dipole (ED) and magnetic dipole (MD) modes that can be used to control scattering and achieve narrowband absorption. In this work, a high-absorptance device is proposed and realized by using amorphous silicon nanoantenna (a-Si NA) arrays that suppress backward and forward scattering with engineered structures and in particular periods. The overlap of ED and MD resonances, by designing an array with a specific period and exciting lattice resonances, is experimentally demonstrated. The absorptance of a-Si NA arrays increases 3-fold in the near-infrared range in comparison to unpatterned silicon films. Nonradiating a-Si NA arrays can achieve high absorptance with a small resonance bandwidth (Q = 11.89) at a wavelength of 785 nm. The effect is observed not only due to the intrinsic loss of material but by overlapping the ED and MD resonances.
Optimization of effective absorption enhancement of paired-strips gold nanoantennas arrays in organic thin-films
(2018-01-01)
Yang, Zih-Ying
;
Su, Chen-Wei
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Chen, Kuo-Ping
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光電系統研究所
;
影像與生醫光電研究所
This study sought to optimize the dimensional characteristics of paired-strips gold nanoantennas embedded in a P3HT:PCBM thin-film by taking into account the tradeoff between the size of the nanostructures and absorber layer as well as the gaps between nanoparticles, to maximize the effective absorption enhancement. The average enhancement behavior within the working region was discussed using integral analysis, which is important for overall enhancement. The discussion would focus on comparing the bands' features of paired-strips nanoantennas embedded in a dielectric thin-film, and in air. By the average absorption 3D slices plots, in which the dimension width, height, and gap are changed with a fixed wavelength; the optimized dimension of paired-strips nanoantennas could be realized. Fixing the period (400 nm) of paired-strips nanoantennas embedded in P3HT:PCBM thin-films (120 nm in thickness) enhanced absorption by 9.8 times.
Room temperature fabrication of titanium nitride thin films as plasmonic materials by high-power impulse magnetron sputtering
(2016-02-01)
Yang, Zih-Ying
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Chen, Yi-Hsun
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Liao, Bo-Huei
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Chen, Kuo-Ping
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照明與能源光電研究所
High-power impulse magnetron sputtering (HiPIMS) was used to deposit titanium nitride (TiN) thin films with high electron density as alternative plasmonic materials. TiN thin films with thicknesses of 20-40 nm were deposited with different average sputtering powers, and exhibited metallic-and dielectric-like optical properties. When the sputtering power was increased from 80 W to 300 W, denser polycrystalline TiN thin films were obtained at room temperature (RT) with a conductivity 25 times that of the low-sputtering-power film. With sufficient average power (>= 180 W), the films exhibited metallic-like optical properties, and a conductivity of >10(5) S/m. By using HiPIMS deposition, good-quality metallic-like TiN thin films could be fabricated at RT without heating the substrate. (C) 2016 Optical Society of America