Browsing by Issue Date, starting with "2016-05-16"

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可見光通訊系統與方法
(2016-05-16)
陳彥安
;
張逸廷
;
曾煜棋
可見光通訊系統包含控制裝置與一或多個傳送裝置。控制裝置配發待傳送的一資料至傳送裝置其一。每一傳送裝置包含編碼模組與發光模組。配發有該資料的傳送裝置的編碼模組將用於分碼多重存取的第一碼轉換成用於可見光通訊的第二碼，並依據第二碼編碼該資料，其發光模組則在亮與暗態間選擇性地切換，以傳送編碼後的該資料。第一碼具雙極性且關聯於配發有該資料的傳送裝置。第二碼具單極性。一例中系統更包含接收裝置接收至少部份來自上述傳送裝置的可見光訊號，將至少部份的可見光訊號由單極性轉換成雙極性，並依據第一碼解碼以取得該資料。
Compact spectrometer system based on a gradient grating period guided-mode resonance filter
(2016-05-16)
Lin, Hsin-An
;
Hsu, Hsin-Yun
;
Chang, Chih-Wei
;
Huang, Cheng-Sheng
;
機械工程學系
We demonstrate a compact spectrometer system by using a gradient grating period guided-mode resonance filter-mounted on a linear photodetector array-that exhibits spatially dependent resonance characteristics; a specific incident wavelength is reflected such that the underlying array pixels measure minimum intensity. A precalibrated transmission efficiency matrix is used to determine each pixel's transmission efficiency for specific wavelengths. Unknown spectral information can be calculated from the measured intensity. Grating periods of 250-388 nm in 2-nm increments are used in each 100-cycle period. Device length is 2.23 mm. Spectral range of 506-700 nm is measurable with 1-nm resolution. (C) 2016 Optical Society of America
Using single side-band modulation for colorless OFDM-WDM access network to alleviate Rayleigh backscattering effects
(2016-05-16)
Yeh, Chien-Hung
;
Chow, Chi-Wai
;
光電工程學系
;
光電工程研究所
;
Department of Photonics
In this investigation, we demonstrate a new colorless orthogonal-frequency-division-multiplexing (OFDM) wavelength-division-multiplexing passive optical network (WDM-PON) system with Rayleigh backscattering (RB) noise mitigation. Here, only a single laser source at the central office (CO) is needed to produce the downstream signal and distributed continuous-wave (CW) carrier, which will then be modulated at the optical networking unit (ONU) to produce the upstream signal. Single side-band (SSB) modulation is used to wavelength-shift the distributed CW carrier, which will be launched into a reflective semiconductor optical amplifier (RSOA) based ONU for directly modulation of 5.15 Gbps OFDM upstream signal. To avoid the radio-frequency (RF) power fading and chromatic fiber dispersion, the four-band OFDM modulation is proposed to generate a 40 Gbps downstream when a Mach-Zehnder modulator (MZM) with -0.7 chirp parameter is used. Hence, the RB circumvention can be centralized in the CO. Moreover, the signal performances of downstream and upstream are also studied and discussed in this measurement. (C) 2016 Optical Society of America
具動態編碼之無線網路傳輸壓縮方法
(2016-05-16)
陳志成
;
徐瑞壕
;
石維倫
;
秦睿志
;
簡群
一種具動態編碼之無線網路傳輸壓縮方法，係用於傳輸一封包至用戶端，透過無線接入點可將所有傳送給用戶端的封包切成固定長度的資料區塊，並將每個資料區塊的重複次數進行統計為每個重複的區塊建立霍夫曼編碼，以代表相對應資料區塊的編碼。因此，在傳送封包前會先進行切塊並且比對是否有重複的資料區塊已被編碼，並將編碼的封包以及使用的編碼進行傳送，而當重複區塊的編碼資訊在傳送給一個特定的用戶端時，也同時會被相同傳輸範圍內的其他用戶端接收到，因此其他用戶端也可以直接儲存此重複區塊以及其編碼，並還原原始的重複區塊內容。
高電子遷移率電晶體及其製造方法
(2016-05-16)
張翼
;
林岳欽
;
謝廷恩
本發明提供一種高電子遷移率電晶體，以閘極掘入結構搭配高介電常數氧化層以及氮化物介面鈍化層，具有高臨界電壓、高轉導、高穩定之汲極輸出電流以及高可靠度等特性及優點。
Omnidirectional, polarization-independent, ultra-broadband metamaterial perfect absorber using field-penetration and reflected-wave-cancellation
(2016-05-16)
Zhong, Yan Kai
;
Lai, Yi-Chun
;
Tu, Ming-Hsiang
;
Chen, Bo-Ruei
;
Fu, Sze Ming
In this work, we present the result of nickel (Ni)-based metamaterial perfect absorbers (MPA) with ultra-broadband close-to-one absorbance. The experimental broadband characteristic is significantly improved over the past effort on metamaterial perfect absorbers. An indepth physical picture and quantitative analysis is presented to reveal the physical origin of its ultrabroadband nature. The key constituent is the cancellation of the reflected wave using ultra-thin, moderate-extinction metallic films. The ultra-thin metal thickness can reduce the reflection as the optical field penetrates through the metallic films. This leads to minimal reflection at each ultra-thin metal layer, and light is penetrating into the Ni/SiO2 stacking. More intuitively, when the layer thickness is much smaller than the photon wavelength, the layer is essentially invisible to the photons. This results in absorption in the metal thin-film through penetration while there is minimal reflection by the metal film. More importantly, the experimental evidence for omni-directionality and polarization-insensitivity are established for the proposed design. Detailed measurement is conducted. Due to the ultrathin metal layers and the satisfactory tolerance in dielectric thickness, the broadband absorption has minimal degradation at oblique incidence. Such a wide angle, polarization-insensitive, ultra-broadband MPA can be very promising in the future, and the optical physics using sub-skin-depth metal film can also facilitate miniaturized high-performance nano-photonic devices. (C) 2016 Optical Society of America.
Stick-Slip Motion of the Wigner Solid on Liquid Helium
(2016-05-16)
Rees, David G.
;
Beysengulov, Niyaz R.
;
Lin, Juhn-Jong
;
Kono, Kimitoshi
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電子物理學系
We present time-resolved transport measurements of a Wigner solid (WS) on the surface of liquid helium confined in a micron-scale channel. At rest, the WS is "dressed" by a cloud of quantized capillary waves (ripplons). Under a driving force, we find that repeated WS-ripplon decoupling leads to stick-slip current oscillations, the frequency of which can be tuned by adjusting the temperature, pressing electric field, or electron density. The WS on liquid He is a promising system for the study of polaronlike decoupling dynamics.
Nonequilibrium and nonlinear defect states in microcavity-polariton condensates
(2016-05-18)
Chen, Ting-Wei
;
Jheng, Shih-Da
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Hsieh, Wen-Feng
;
Cheng, Szu-Cheng
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物理研究所
The nonequilibrium and nonlinear defect modes (NNDMs), localized by a defect in a nonequilibrium microcavity-polariton condensate (MPC), are studied. There are three analytic solutions of NNDMs in a point defect: the bright NNDM, a bound state with two dark solitons for an attractive potential, and a gray soliton bound by a defect for a repulsive potential. We find that the stable NNDMs in a nonequilibrium MPC are the bright NNDM and gray soliton bound by a defect. The bright NNDM, which has the hyperbolic cotangent form, is a bright localized state existing in a uniform MPC. The bright NNDM is a unique state occurring in a nonequilibrium MPC that has pump-dissipation and repulsive-nonlinearity characters. No such state can exist in an equilibrium system with repulsive nonlinearity.
Bound-bound transitions in the emission spectra of Ba+-He excimer
(2016-05-19)
Moroshkin, P.
;
Kono, K.
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物理研究所
;
Institute of Physics
We present an experimental and theoretical study of the emission and absorption spectra of the Ba+ ions and Ba+*He excimer quasimolecules in the cryogenic Ba-He plasma. We observe several spectral features in the emission spectrum, which we assign to the electronic transitions between bound states of the excimer correlating to the 6(2)P(3/2) and 5(2)D(3/2,5/2) states of Ba+. The resulting Ba+(5(2)D(J)) He is a metastable electronically excited complex with orbital angular momentum L = 2, thus expanding the family of known metal-helium quasimolecules. It might be suitable for high-resolution spectroscopic studies and for the search for new polyatomic exciplex structures.
交大e-News第209期-頒贈盧明光董事長名譽博士學位
(2016-05-20)
國立交通大學秘書室
;
Secretariat
Hybrid photonic crystal light-emitting diode renders 123% color conversion effective quantum yield
(2016-05-20)
Krishnan, C.
;
Brossard, M.
;
Lee, K. -Y.
;
Huang, J. -K.
;
Lin, C. -H.
Colloidal quantum dots (QDs) have emerged as promising color conversion light emitters for solid-state lighting applications [Nat. Photonics 7, 13 (2012) due to their emission tunability and near-unity photoluminescence quantum yields. In the current commercial LEDs, QDs are dispersed into an encapsulation layer in a far-field architecture, where the majority of the light emitted by the LED remains trapped within the epitaxy due to total internal reflection, drastically reducing the out-coupling efficiency. In this paper, we demonstrate a photonic quasi-crystal hybrid LED geometry that allows QD emitters to be placed in close proximity to the multiple quantum wells (MQWs) of the active area. This architecture greatly improves the coupling between MQWs and QDs, simultaneously allowing for a non-radiative resonant energy transfer between the MQWs and the QDs and near-field radiative coupling of trapped ( guided) modes in the LED to the emitters. In this configuration, we demonstrate record-breaking effective quantum yields reaching 123% for single-color conversion LEDs and 110% for white light-emitting devices. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article\'s title, journal citation, and DOI.
A Novel Metallo-beta-Lactamase Involved in the Ampicillin Resistance of Streptococcus pneumoniae ATCC 49136 Strain
(2016-05-23)
Chang, Chia-Yu
;
Lin, Hui-Jen
;
Li, Bor-Ran
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Li, Yaw-Kuen
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分子醫學與生物工程研究所
Streptococcus pneumoniae, a penicillin-sensitive bacterium, is recognized as a major cause of pneumonia and is treated clinically with penicillin-based antibiotics. The rapid increase in resistance to penicillin and other antibiotics affects 450 million people globally and results in 4 million deaths every year. To unveil the mechanism of resistance of S. pneumoniae is thus an important issue to treat streptococcal disease that might consequently save millions of lives around the world. In this work, we isolated a streptococci-conserved L-ascorbate 6-phosphate lactonase, from S. pneumoniae ATCC 49136. This protein reveals a metallo-beta-lactamase activity in vitro, which is able to deactivate an ampicillin-based antibiotic by hydrolyzing the amide bond of the beta-lactam ring. The Michaelis parameter (K-m) = 25 mu M and turnover number (k(cat)) = 2 s(-1) were obtained when nitrocefin was utilized as an optically measurable substrate. Through confocal images and western blot analyses with a specific antibody, the indigenous protein was recognized in S. pneumoniae ATCC 49136. The protein-overexpressed S. pneumonia exhibits a high ampicillin-tolerance ability in vivo. In contrast, the protein-knockout S. pneumonia reveals the ampicillin-sensitive feature relative to the wild type strain. Based on these results, we propose that this protein is a membrane-associated metallo-beta-lactamase (MBL) involved in the antibiotic-resistant property of S. pneumoniae.
Electrohydrodynamics of a viscous drop with inertia
(2016-05-23)
Nganguia, H.
;
Young, Y. -N.
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Layton, A. T.
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Lai, M. -C.
;
Hu, W. -F.
Most of the existing numerical and theoretical investigations on the electrohydrodynamics of a viscous drop have focused on the creeping Stokes flow regime, where nonlinear inertia effects are neglected. In this work we study the inertia effects on the electrodeformation of a viscous drop under a DC electric field using a novel second-order immersed interface method. The inertia effects are quantified by the Ohnesorge number Oh, and the electric field is characterized by an electric capillary number Ca E. Below the critical Ca E, small to moderate electric field strength gives rise to steady equilibrium drop shapes. We found that, at a fixed Ca E, inertia effects induce larger deformation for an oblate drop than a prolate drop, consistent with previous results in the literature. Moreover, our simulations results indicate that inertia effects on the equilibrium drop deformation are dictated by the direction of normal electric stress on the drop interface: Larger drop deformation is found when the normal electric stress points outward, and smaller drop deformation is found otherwise. To our knowledge, such inertia effects on the equilibrium drop deformation has not been reported in the literature. Above the critical Ca E, no steady equilibrium drop deformation can be found, and often the drop breaks up into a number of daughter droplets. In particular, our Navier-Stokes simulations show that, for the parameters we use, (1) daughter droplets are larger in the presence of inertia, (2) the drop deformation evolves more rapidly compared to creeping flow, and (3) complex distribution of electric stresses for drops with inertia effects. Our results suggest that normal electric pressure may be a useful tool in predicting drop pinch-off in oblate deformations.
Geometry-dependent phase, stress state and electrical properties in nickel-silicide nanowires
(2016-05-25)
Wang, C. C.
;
Lai, W. T.
;
Hsiao, Y. Y.
;
Chen, I. H.
;
George, T.
We report that the geometry of single-crystalline Si nanowires (NWs) prior to salicidation at 500 degrees C is the key factor controlling the phase, stress state, and electrical resistivity of the resulting NixSiy NWs of width less than 100 nm. This is a radical departure from previous observations of a single phase formation for nickel silicides generated from the silicidation of bulk Si substrates. The phase transition from NiSi for large NWs (W-Si NW = 250-450 nm) to Ni2Si for small NWs (W-Si NW = 70-100 nm) is well correlated with the observed volumetric expansion and electrical resistivity variation with the NW width. For the extremely small dimensions of NixSiy NWs, we propose that the preeminent, kinetics-based Zhang and d\'Heurle model for salicidation be modified to a more thermodynamically-governed, volume-expansion dependent NixSiy phase formation. A novel, plastic deformation mechanism is proposed to explain the observed, geometry-dependent NixSiy NW phase formation that also strongly influences the electrical performance of the NWs.
Intersystem crossing-branched excited-state intramolecular proton transfer for o-nitrophenol: An ab initio on-the-fly nonadiabatic molecular dynamic simulation
(2016-05-25)
Xu, Chao
;
Yu, Le
;
Zhu, Chaoyuan
;
Yu, Jianguo
;
Cao, Zexing
The 6SA-CASSCF(10, 10)/6-31G (d, p) quantum chemistry method has been applied to perform on-the-fly trajectory surface hopping simulation with global switching algorithm and to explore excited-state intramolecular proton transfer reactions for the o-nitrophenol molecule within low-lying electronic singlet states (S-0 and S-1) and triplet states (T-1 and T-2). The decisive photoisomerization mechanisms of o-nitrophenol upon S-1 excitation are found by three intersystem crossings and one conical intersection between two triplet states, in which T-1 state plays an essential role. The present simulation shows branch ratios and timescales of three key processes via T-1 state, non-hydrogen transfer with ratio 48% and timescale 300 fs, the tunneling hydrogen transfer with ratios 36% and timescale 10 ps, and the direct hydrogen transfer with ratios 13% and timescale 40 fs. The present simulated timescales might be close to low limit of the recent experiment results.
Optimized Spiral Metal-Gallium-Nitride Nanowire Cavity for Ultra-High Circular Dichroism Ultraviolet Lasing at Room Temperature
(2016-05-25)
Liao, Wei-Chun
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Liao, Shu-Wei
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Chen, Kuo-Ju
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Hsiao, Yu-Hao
;
Chang, Shu-Wei
Circularly polarized laser sources with small footprints and high efficiencies can possess advanced functionalities in optical communication and biophotonic integrated systems. However, the conventional lasers with additional circular-polarization converters are bulky and hardly compatible with nanophotonic circuits, and most active chiral plasmonic nanostructures nowadays exhibit broadband emission and low circular dichroism. In this work, with spirals of gallium nitride (GaN) nanowires (NWRs) covered by a metal layer, we demonstrated an ultrasmall semiconductor laser capable of emitting circularly-polarized photons. The left-and right-hand spiral metal nanowire cavities with varied periods were designed at ultraviolet wavelengths to achieve the high quality factor circular dichroism metastructures. The dissymmetry factors characterizing the degrees of circular polarizations of the left-and right-hand chiral lasers were 1.4 and -1.6 (+/- 2 if perfectly circular polarized), respectively. The results show that the chiral cavities with only 5 spiral periods can achieve lasing signals with the high degrees of circular polarizations.
Enzyme Catalysis that Paves the Way for S-Sulfhydration via Sulfur Atom Transfer
(2016-05-26)
Huang, Gou-Tao
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Yu, Jen-Shiang K.
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生物科技學系
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生物資訊及系統生物研究所
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Department of Biological Science and Technology
S-sulfhydration is generally anticipated to proceed through the transfer of the SH group (Nu-SH center dot center dot center dot S--R -> Nu(-)center dot center dot center dot HS-S-R). The other route involves the sulfur atom (5) transfer between two sulfhydryl anions (Nu-S-center dot center dot center dot S--R -> Nu(-)center dot center dot center dot S--S-R) and is considered electrostatically unfavorable. Mercaptopyruvate sulfurtransferase (MST, PDB code: 4JGT) catalyzes sulfur transfer from mercaptopyruvate to sulfur acceptors, and the first step of the reaction is the formation of cysteine (Cys248) persulfide via S-sulfhydration. Mechanistic studies on S-sulfhydration in MST using QM/MM methods show that the sulfur atom transfer initialized by the deprotonation of the Ser250/His74/Asp63 triad is kinetically preferred to the SH-promoted sulfur transfer. The calculated barrier of approximately 16 kcal mol(-1) for the S-0 transfer agrees well with experimental results. The electrostatic repulsion during the S-0 transfer can be sophisticatedly reduced by the aid of the Cys248-Gly249-Ser250-Gly251-Val252-Thr253 (CGSGVT) loop. Electrostatic potentials and frontier orbitals are also analyzed for the persulfide anion surrounded by the loop. The sulfur atom transfer which is seldom regarded possible is therefore facilitated with the assistance of the triad and the loop in the enzyme.
Short wavelength enhanced phototransistor with n-doped porous silicon layer
(2016-05-26)
Wang, Yao-Chin
;
Lin, Bor-Shyh
;
Yang, Zu-Po
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光電學院
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College of Photonics
A phototransistor with aluminium (Al)/porous silicon (Si)/epitaxial-Si structures was proposed and was fabricated and characterised with short wavelength enhanced operating. We proposed the short wavelength response of the Si-based thin film phototransistor; it can be enhanced by introducing thin porous Si (PS) layer as the base region of transistor. The porous process of device manufacture is suitable for applications in design of visible-light sensitive phototransistors. Experimental results showed that the short wavelength responses in the developed devices were enhanced as compared with the Si-based homojunction transistors, this comparably medium optical gain indicated that the developed Al/PSi/epitaxial-Si heterojunction thin film phototransistor got potential for practical Si-based optical-electron integrated-circuit and biophotonics applications.
A theoretical and experimental evaluation of surface roughness variation in trigate metal oxide semiconductor field effect transistors
(2016-05-28)
Hsieh, E. R.
;
Chung, Steve S.
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A gate current variation measurement method is proposed to examine the surface roughness of metal oxide semiconductor field effect transistors (MOSFETs). This gate current variation is demonstrated on the trigate structure MOSFETs. It was found that the standard deviation of oxide-thickness is proportional to the inverse of square-root of device areas, and its slope is defined as the effective surface roughness variation. In particular, for the transistors with varying fin height, this surface roughness effect aggravates with the increasing fin height. More importantly, the gate leakage at off-state, i.e., Vg = 0V, is strongly dependent on the gate dielectric surface roughness and dominates the drain current variations. This gate leakage may serve as a quality measure of a low power and energy efficient integrated circuit, especially for the transistor with 3-dimensional gate structure. The present results provide us better understandings on an additional source of V-th fluctuations, i.e., the surface roughness variation, in addition to the random dopant fluctuation, that we are usually not noticed. In particular, this study also provides us a simple easy-to-use method for the monitoring of oxide quality in the volume production of trigate MOSFETs. Published by AIP Publishing.
臺灣電影　從低谷中爬起
(2016-05-29)
許凱智
;
Department of Communication and Technology
;
傳播與科技學系
臺灣電影發展多年，過程中遇到許多問題，而臺灣的電影人，是如何準備和面對這些難關？