Browsing by Author "Chen, Kuo-Ping"

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4 Tunability and Optimization of Coupling Efficiency in Tamm Plasmon Modes
(2015-07-01)
Chang, Che-Yuan
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Chen, Yi-Hsuan
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Tsai, Yu-Lin
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Kuo, Hao-Chung
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Chen, Kuo-Ping
A Tamm plasmon polariton is a plasmonic resonance excited at the boundary between a photonic crystal and a metal. In this paper, a novel approach based on admittance loci is proposed to demonstrate the relation between thin-film structures and the corresponding Tamm plasmon modes. The tunability of the resonance wavelength and optimization of coupling efficiency are demonstrated. In addition, by using different metals to couple Tamm plasmon modes in the visible spectrum, silver has 4.7 times larger Q-factor than gold and 84 times larger than aluminum at 700 nm. The near-field enhancement of silver Tamm plasmon modes could be up to eight times larger than incident EM waves.
Absorption avoided resonance crossing of hybridization of silicon nanoparticles and gold nanoantennas
(2019-08-13)
Yang, Jhen-Hong
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Yu, Min-Wen
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Chen, Kuo-Ping
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光電系統研究所
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照明與能源光電研究所
The near-field coupling between a high-refractive-index nanoparticle and gold nanoantennas is investigated theoretically. The absorption enhancement and also avoided resonance crossing in the absorption cross section spectra were observed with the hybridization system due to the coupling between the localized surface plasmon resonance of the gold nanoantennas and the magnetic dipole resonance of the silicon nanoparticle. By controlling the nanoparticle size or the separation distance, the near-field coupling can be tuned from the weak to the strong regime.
Broadband gold nanoantennas arrays with transverse dimension effects
(2016-08-08)
Su, Chen-Wei
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Chen, Kuo-Ping
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光電系統研究所
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影像與生醫光電研究所
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Institute of Photonic System
Broadband resonance in gold paired-rods nanoantennas and paired-strips gratings is investigated when the nanostructure's transverse (non-polarization) dimension is changed from paired-rods to paired-strips. Increasing the transverse dimension blue shifts the resonance wavelength and widens its bandwidth due to cancellation of the magnetic field between nanoantennas. A derived resistor-inductor-capacitor (RLC) equivalent circuit model verifies the nanostructures' resonance when elongating the transverse dimensions. Paired-strips gratings have a bandwidth 2.04 times that of paired-rods nanoantennas. (C) 2016 Optical Society of America
Controllable Tamm Plasmon Effect Designed by Admittance Loci
(2014-01-01)
Chang, Che-Yuan
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Chen, Kuo-Ping
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影像與生醫光電研究所
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Institute of Imaging and Biomedical Photonics
Tamm plasmon is a plasmonic resonance happens at the boundary of photonic crystal and metal. In this work, a novel design tool based on admittance loci is proposed to demonstrate the relationship between Tamm plasmon structure and the corresponding resonance effect. The tunability of resonance wavelengths and the optimization of coupling efficiency are presented.
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
;
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
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Chen, Kuo-Ping
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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
Electrically active nanoantenna array enabled by varying the molecular orientation of an interfaced liquid crystal
(2016-01-01)
Hsiao, Yu-Cheng
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Su, Chen-Wei
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Yang, Zong-Han
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Cheypesh, Yevheniia I.
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Yang, Jhen-Hong
A system comprising a gold nanoantenna array covered with a high-birefringence liquid crystal (LC) material is introduced. By applying voltage across the LC bulk, we demonstrate that the refractive-index and polarization changes significantly modify the hybrid plasmonic-photonic resonances in the system. The hybrid structure enables the active control of the spectrum as well as a large shift in resonance wavelength of the metallic nanoantennas by means of an externally applied electric field. Our modeling supports the observed results, by assuming that the nanoantenna array leads to two orthogonal easy axes with a finite anchoring energy. In combination of the nanostructured surface with birefringent LC, tunability up to 90 nm is achieved in the visible wavelengths, opening the door towards nanoscale displays or nano-optical switches.
Electrically tunable transmission of gold binary-grating metasurfaces integrated with liquid crystals
(2016-07-25)
Chen, Kuo-Ping
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Ye, Shi-Cheng
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Yang, Chi-Yin
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Yang, Zong-Han
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Lee, Wei
Planar photonics using metasurfaces is of great interest because a metasurface can control the flow of light beyond that attainable with natural materials. The resonance wavelength of a binary-grating metasurface is adjustable by changing the width and thickness of the nanostructure. We propose a novel combination of nematic liquid crystals and a binary-grating metasurface with which the diffraction efficiency can be controlled by adjusting the applied voltage. (C) 2016 Optical Society of America
Enhancing the Interaction between High-Refractive Index Nanoparticles and Gold Film Substrates Based on Oblique Incidence Excitation
(2016-10-01)
Kuo, Yu-Lun
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Chuang, Shih-Yi
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Chen, Shiuan-Yeh
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Chen, Kuo-Ping
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照明與能源光電研究所
We investigate the coupling of dipole resonances induced in a heteromaterial system composed of a high-refractive-index nanoparticle and a highly reflective substrate. A broad scattering signal and strong electric nearfield enhancement in the near-infrared region are generated by a hybrid Si nanoparticle on a gold-film system under oblique illumination. Dark-field microscopy investigations of the scattering signal measurement reveal the resonance shifts of the dipole mode of silicon nanoparticles on gold films. Further, the scattering signal is enhanced for p-polarized illumination in the near-infrared region. The results indicate that the coupling of Si nanoparticles on a gold-film system facilitates a possible application for both surface-enhanced fluorescence and surface-enhanced Raman scattering.
Evanescent Wave-Assisted Symmetry Breaking of Gold Dipolar Nanoantennas
(2016-09-01)
Yang, Jhen-Hong
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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
;
Institute of Photonic System
Symmetry-breaking and scattering cancellation were observed in the dark-mode resonance of dipolar gold nanoantennas (NAs) on glass substrates coupled with oblique incidence and total internal reflection. With the assistance of evanescent waves, the coupling efficiency was twice as strong when the incidence angle was larger than the critical angle. The Hamiltonian equation and absorption spectra were used to analyze the hybridization model of symmetric dipolar gold NAs. The antibonding mode could be coupled successfully by both transverse-magnetic (TM) and transverse-electric (TE) polarizations to NAs when the dimers orientation is parallel to the propagation direction of evanescent waves.
Fano feature induced by a bound state in the continuum via resonant state expansion
(2020-08-13)
Pankin, Pavel S.
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Maksimov, Dmitrii N.
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Chen, Kuo-Ping
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Timofeev, Ivan, V
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影像與生醫光電研究所
We consider light scattering by an anisotropic defect layer embedded into anisotropic photonic crystal in the spectral vicinity of an optical bound state in the continuum (BIC). Using a resonant state expansion method we derive an analytic solution for reflection and transmission amplitudes. The analytic solution is constructed via a perturbative approach with the BIC as the zeroth order approximation. The solution is found to describe the collapsing Fano feature in the spectral vicinity of the BIC. The findings are confirmed via comparison against direct numerical simulations with the Berreman transfer matrix method.
Giant photothermal nonlinearity in a single silicon nanostructure
(2020-08-14)
Duh, Yi-Shiou
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Nagasaki, Yusuke
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Tang, Yu-Lung
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Wu, Pang-Han
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Cheng, Hao-Yu
Silicon photonics have attracted significant interest because of their potential in integrated photonics components and all-dielectric meta-optics elements. One major challenge is to achieve active control via strong photon-photon interactions, i.e. optical nonlinearity, which is intrinsically weak in silicon. To boost the nonlinear response, practical applications rely on resonant structures such as microring resonators or photonic crystals. Nevertheless, their typical footprints are larger than 10 mu m. Here, we show that 100nm silicon nano-resonators exhibit a giant photothermal nonlinearity, yielding 90% reversible and repeatable modulation from linear scattering response at low excitation intensities. The equivalent nonlinear index is five-orders larger compared with bulk, based on Mie resonance enhanced absorption and high-efficiency heating in thermally isolated nanostructures. Furthermore, the nanoscale thermal relaxation time reaches nanosecond. This large and fast nonlinearity leads to potential applications for GHz all-optical control at the nanoscale and super-resolution imaging of silicon.
Graphene-Loaded Plasmonic Zirconium Nitride and Gold Nanogroove Arrays for Surface-Charge Modifications
(2020-06-26)
Yu, Min-Wen
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Ishii, Satoshi
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Ku, Ji-Ren
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Yang, Jhen-Hong
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Huang, Chih-Hsiang
Graphene-on-metal (G/M) heterostructures have gained considerable attention in recent years owing to their outstanding optical and electrical properties. In this study, the polarity of graphene doping to different metallic materials underneath graphene is analyzed for applications in surface-charge modifications. Kelvin probe force microscopy clearly reveals the charge-transfer effects of plasmonic zirconium nitride (ZrN) and gold (Au) on the formation of G/M heterostructures. In addition, both ZrN and Au nanogroove arrays are fabricated by focused ion beam to generate surface plasmon resonances. The charge-transfer effects influence the effective permittivities of ZrN and Au surfaces such that opposite plasmonic resonance shifts are demonstrated for the ZrN and Au nanogroove arrays. Our results show that the choice of metallic material is important for achieving a desired charge transfer in the loading of graphene onto metallic materials.
High Sensitivity Dark Mode Plasmonic Resonance of Gold Nanoantennas Arrays in Evanescent Waves
(2015)
Chen, Kuo-Ping
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Chen, Yi-Hsun
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Kuo, Yu-Lun
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Yang, Zhen-hong
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Chang, Che-Yuan
Plasmonic dark modes of gold nanoantennas are observed in evanescent waves. Comparing with the bright mode for normal incidence of nanoantennas, dark mode resonance not only has a higher extinction coefficient but also achieves higher sensitivity to the surrounding environment. The sensitivity of the dark mode of gold nanoantenna is 4.84 times that of the bright mode in terms of the figure of merit.
High-Performance Plasmonic Nanolasers with a Nanotrench Defect Cavity for Sensing Applications
(2018-07-01)
Cheng, Pi-Ju
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Huang, Zhen-Ting
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Li, Jhu-Hong
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Chou, Bo-Tsun
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Chou, Yu-Hsun
Recent developments in small footprint plasmonic nanolasers show promise for active optical sensing with potential applications in various fields, including real-time and label-free biochemical sensing, and gas detection. In this study, we demonstrate a novel hybrid plasmonic crystal nanolaser that features a ZnO nanowire placed on Al grating surfaces with a nanotrench defect nanocavity. The lasing action of gain-assisted defect nanocavity overcomes the ohmic loss parasitically in the plasmonic nanostructures. Therefore, the plasmonic nanolaser exhibits an extremely small mode volume, a narrow linewidth Delta lambda, and a high Purcell factor that can facilitate the strong interaction between light and matter. This can be used as a refractive index sensor and is highly sensitive to local changes in the refractive indices of ambient materials. By careful design, the near-ultraviolet nanolaser sensors have significant sensing performances of glucose solutions, revealing a high sensitivity of 249 nm/RIU and high resolution, with a figure of merit of 1132, at the resonant wavelength of 373 nm.
Hybridization models of gold nanoantennas arrays in polarization dependent evanescent waves
(2015-01-01)
Chen, Kuo-Ping
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Chen, Yi-Hsun
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Chang, Che-Yuan
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Kuo, Yu-Lun
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Yang, Zhen-hong
The plasmonic coupling of nanoantennas could be explained by the plasmon hybridization model introduced. For symmetric nanoparticles pairs, the coupled mode can be shifted to higher or lower frequencies, depending on the phase of the fields from each nanoparticle. In p-polarization, the in-phase response is called bonding mode and out of phase response is called antibonding mode, which are analogous to the molecular orbital theory. The bonding mode, located at a lower energy level, could be strongly excited by normal incidence, but antibonding mode, located at a higher energy level, could hardly excited by normal incident plane wave and which is not easy to be observed. In literatures, the antibonding mode could only be excited by highly focused laser beams, the radiation from a local emitter, and the evanescent field produced by total internal reflection9. Although the observation is not easy, the antibonding mode has brought a lot of attention because of the slower radiative decay and narrower linewidths. However, there are not many researches discussing the sensor application of the plasmonic antibonding mode of nanoantenans arrays. In this work, gold nanoantennas antibonding mode in TM and TE polarized evanescent field is investigated and the sensitivity to the refractive index change of surrounding medium is compared to bonding mode in normal incidence. Furthermore, in normal incidence, due to the impedance mismatch between the dielectric and substrate, strong reflectance happens at the resonance in bonding mode which could reduce the coupling efficiency. In order to achieve higher energy coupling efficiency, total internal reflection could be used to minimize the impedance mismatch and transfer the input energy into antibonding mode plasmonic resonance.
Liquid-Crystal Active Tamm-Plasmon Devices
(2018-06-20)
Cheng, Hao-Chi
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Kuo, Ching-Yung
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Hung, Yu-Ju
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Chen, Kuo-Ping
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Jeng, Shie-Chang
We demonstrate a liquid-crystal (LC)-tuned Tamm-plasmon (TP) resonance device. The term TP polariton refers to plasmonic resonance at the interface between a photonic crystal (PC) and a metallic film. We formulate a precise optical analysis of the proposed device using the transfer-matrix method. A single resonance dip in the photonic band-gap region guarantees that the thickness of the LC layer between the PC and the metallic film can be as small as about 180 nm. Tuning phase retardation in the LC layer is shown to shift the resonance wavelength tens of nanometers, depending on the birefringence and width of the LC layer. Simulation results are in good agreement with the experimental data.
Liquid-crystal tunable color filters based on aluminum metasurfaces
(2017-11-27)
Xie, Zu-Wen
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Yang, Jhen-Hong
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Vashistha, Vishal
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Lee, Wei
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Chen, Kuo-Ping
Designing color pixels using plasmonic nanostructures and metasurfaces has become a luring area of research in recent years. Here, we experimentally demonstrated the voltage tunability of a dynamic plasmonic color filter by using an aluminum grating integrated with the nematic liquid crystal (LC). Along with a typical substrate coated with rubbed polyimide film, the aluminum grating itself serves as a molecular alignment layer to form a twisted LC cell. This hybrid structure allows electrically controlled transmission color by applying the voltage. A significant spectral tunability of such a device has been demonstrated by applying the small voltage from 0 to 4 V-rms. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
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
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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.