Browsing by Issue Date, starting with "2009-02-02"

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WDM up-conversion employing frequency quadrupling in optical modulator
(2009-02-02)
Shih, Po-Tsung
;
Lin, Chun-Ting
;
Jiang, Wen-Jr
;
Chen, Jason (Jyehong)
;
Huang, Han-Sheng
This work presents an optical up-conversion system with frequency quadrupling for wavelength-division-multiplexing (WDM) communication systems using a dual-parallel Mach-Zehnder modulator without optical filtering. Four-channel 1.25-Gb/s wired fiber-to-the-x (FTTx) and wireless radio-over-fiber (RoF) signals are generated and transmitted simultaneously. Moreover, the decline in receiver sensitivities due to Mach-Zehnder modulator bias drifts is also investigated. Receiver power penalties of the 20-GHz up-converted WDM signals and baseband (BB) FTTx signals are less than 1 dB when bias deviation voltage is less the 20% of the half-wave voltage. After transmission over a 50-km SSMF, the receiver power penalties of both the BB and 20-GHz RF OOK signals are less than 1 dB. Notably, 60-GHz optical up-conversion can be achieved using 15-GHz radio frequency (RF) components and equipment. (C) 2009 Optical Society of America
Modulation instability in nonlinear coupled resonator optical waveguides and photonic crystal waveguides
(2009-02-02)
Huang, Chih-Hsien
;
Lai, Ying-Hsiuan
;
Cheng, Szu-Cheng
;
Hsieh, Wen-Feng
;
光電工程學系
Modulation instability (MI) in a coupled resonator optical waveguide (CROW) and photonic-crystal waveguide (PCW) with nonlinear Kerr media was studied by using the tight-binding theory. By considering the coupling between the defects, we obtained a discrete nonlinear evolution equation and termed it the extended discrete nonlinear Schrodinger (EDNLS) equation. By solving this equation for CROWs and PCWs, we obtained the MI region and the MI gains, G(p,q), for different wavevectors of the incident plane wave (p) and perturbation (q) analytically. In CROWs, the MI region, in which solitons can be formed, can only occur for pa being located either before or after square/2, where a is the separation of the cavities. The location of the MI region is determined by the number of the separation rods between defects and the sign of the Kerr coefficient. However, in the PCWs, pa in the MI region can exceed the square/2. For those wavevectors close to square/2, the MI profile, G(q), can possess two gain maxima at fixed pa. It is quite different from the results of the nonlinear CROWs and optical fibers. By numerically solving the EDNLS equation using the 4(th) order Runge-Kutta method to observe exponential growth of small perturbation in the MI region, we found it is consistent with our analytic solutions. (C) 2009 Optical Society of America
Broadband and omnidirectional antireflection from conductive indium-tin-oxide nanocolumns prepared by glancing-angle deposition with nitrogen
(2009-02-02)
Chang, C. H.
;
Yu, Peichen
;
Yang, C. S.
;
光電工程學系
;
Department of Photonics
Characteristic formation of highly oriented indium-tin-oxide (ITO) nanocolumns is demonstrated using electron-beam evaporation with an obliquely incident nitrogen flux. The nanocolumn material exhibits broadband and omnidirectional antireflective characteristics up to an incidence angle of 70 degrees for the 350-900 nm wavelength range for both s- and p-polarizations. Calculations based on a rigorous coupled-wave analysis indicate that the superior antireflection arises from the tapered column profiles which collectively function as a gradient-index layer. Since the nanocolumns have a preferential growth direction which follows the incident vapor flux, the azimuthal and polarization dependence of reflectivities are also investigated. The single ITO nanocolumn layer can function as antireflection contacts for light emitting diodes and solar cells.
Ultra-high sensitivity optical stress sensor based on double-layered photonic crystal microcavity
(2009-02-02)
Lu, Tsan-Wen
;
Lee, Po-Tsung
;
光電工程學系
;
Department of Photonics
In this report, we present the design principles to achieve a highly sensitive optical stress sensor. The structure we use is a double-layered (DL) photonic molecule with optical bonding and anti-bonding states based on whispering-gallery mode in photonic crystal microcavity. By applying finite-difference time-domain and finite-element methods, we simulate the change of optical properties (including wavelength and quality (Q) factor) of bonding mode caused by the DL structural variation due to the applied stress in two DL geometries. In the end, we summarize an optical stress sensor design with high Q factor, large structural response due to the applied stress, and large optical spectrum change due to the DL structural variation. The minimum detectable stress variation is estimated to be as small as 0.95 nN. (C) 2009 Optical Society of America
Subnanosecond mJ eye-safe laser with an intracavity optical parametric oscillator in a shared resonator
(2009-02-02)
Huang, Y. P.
;
Chang, H. L.
;
Huang, Y. J.
;
Chang, Y. T.
;
Su, K. W.
We theoretically verify that the threshold of an intracavity optical parametric oscillator pumped by a passively Q-switched laser is entirely controlled by the bleach of the saturable absorber not by the signal output reflectivity. We use a series of different output couplers to optimize the output performance. With a signal output reflectivity of 15%, we experimentally achieve an efficient subnanosecond eye-safe laser with 3.3 mJ pulse energy and 1.5 MW peak power. @ 2008 Optical Society of America
Effects of thermal annealing on the emission properties of type-II InAs/GaAsSb quantum dots
(2009-02-02)
Liao, Yu-An
;
Hsu, Wei-Ting
;
Chiu, Pei-Chin
;
Chyi, Jen-Inn
;
Chang, Wen-Hao
We report the effects of thermal annealing on the emission properties of type-II InAs quantum dots (QDs) covered by a thin GaAs(1-x)Sb(x) layer. Apart from large blueshifts and a pronounced narrowing of the QD emission peak, the annealing induced alloy intermixing also leads to enhanced radiative recombination rates and reduced localized states in the GaAsSb layer. Evidences of the evolution from type-II to type-I band alignments are obtained from time-resolved and power-dependent photoluminescence measurements. We demonstrate that postgrowth thermal annealing can be used to tailor the band alignment, the wave function overlaps, and hence the recombination dynamics in the InAs/GaAsSb type-II QDs.
Broadband and omnidirectional antireflection from conductive indium-tin-oxide nanocolumns prepared by glancing-angle deposition with nitrogen (Retracted article. See vol. 104, 269901, 2014)
(2009-02-02)
Chang, C. H.
;
Yu, Peichen
;
Yang, C. S.
;
光電工程學系
;
Department of Photonics
Characteristic formation of highly oriented indium-tin-oxide (ITO) nanocolumns is demonstrated using electron-beam evaporation with an obliquely incident nitrogen flux. The nanocolumn material exhibits broadband and omnidirectional antireflective characteristics up to an incidence angle of 70 degrees for the 350-900 nm wavelength range for both s- and p-polarizations. Calculations based on a rigorous coupled-wave analysis indicate that the superior antireflection arises from the tapered column profiles which collectively function as a gradient-index layer. Since the nanocolumns have a preferential growth direction which follows the incident vapor flux, the azimuthal and polarization dependence of reflectivities are also investigated. The single ITO nanocolumn layer can function as antireflection contacts for light emitting diodes and solar cells.
Broadband and omnidirectional antireflection from conductive indium-tin-oxide nanocolumns prepared by glancing-angle deposition with nitrogen (Retracted article. See vol. 104, 269901, 2014)
(2009-02-02)
Chang, C. H.
;
Yu, Peichen
;
Yang, C. S.
;
光電工程學系
;
Department of Photonics
Characteristic formation of highly oriented indium-tin-oxide (ITO) nanocolumns is demonstrated using electron-beam evaporation with an obliquely incident nitrogen flux. The nanocolumn material exhibits broadband and omnidirectional antireflective characteristics up to an incidence angle of 70 degrees for the 350-900 nm wavelength range for both s- and p-polarizations. Calculations based on a rigorous coupled-wave analysis indicate that the superior antireflection arises from the tapered column profiles which collectively function as a gradient-index layer. Since the nanocolumns have a preferential growth direction which follows the incident vapor flux, the azimuthal and polarization dependence of reflectivities are also investigated. The single ITO nanocolumn layer can function as antireflection contacts for light emitting diodes and solar cells.
Closed sulfur circulation system
(2009-02-03)
Lin
;
Jin-Gaw
;
Cheng
;
Hong-Bang
The present invention provides a closed sulfur circulation wastewater treatment system, which combines autotrophic and heterotrophic denitrification to recycle sulfates. Particularly, the present invention provides a process and a system for wastewater treatment which effectively process wastewater having both high nitrates and low organic carbonaceous sources, and effectively reduce sulfates by-products.
Bit error rate tester and pseudo random bit sequences generator thereof
(2009-02-03)
Chen
;
Wei-Zen
;
Huang
;
Guan-Sheng
A bit error rate tester and a pseudo random bit sequences (PRBS) generator thereof are provided. The bit error rate tester includes a transmitter PRBS generator, a master PRBS generator, a slave PRBS generator, a comparator, and a counting unit. The transmitter PRBS generator generates a parallel N-bit (N is an integer larger than 1) original PRBS, wherein an object to be tested receives the original PRBS and outputs a parallel N-bit code to be tested. The master and the slave PRBS generators generate a master and a slave parallel N-bit PRBS, respectively. The comparator receives, compares, and determines whether the code to be tested, the master and the slave PRBS are the same or not, and outputs a comparison result. The counting unit coupling to the comparator counts a number of bit errors based on the comparison result.
OPERATING METHOD APPLIED TO LOW DENSITY PARITY CHECK (LDPC) DECODER AND CIRCUIT THEREOF
(2009-02-05)
LIU, Chih-Hao
;
Liao, Yen-Chin
;
Lee, Chen-Yi
;
Chang, Hsie-Chia
;
Hsu, Yarsun
An operating method applied to low density parity check (LDPC) decoders and the circuit thereof are proposed, in which original bit nodes are incorporated into check nodes for simultaneous operation. The bit node messages are generated according to the different between the newly generated check messages and the previously check node messages. The bit node messages can be updated immediately, and the decoder throughput can be improved. In the other way, the required memory of LDPC decoders can be effectively reduced, and the decoding speed can also be enhanced.
Improved reliability of Mo nanocrystal memory with ammonia plasma treatment
(2009-02-09)
Lin, Chao-Cheng
;
Chang, Ting-Chang
;
Tu, Chun-Hao
;
Chen, Wei-Ren
;
Hu, Chih-Wei
We investigated ammonia plasma treatment influence on the nonvolatile memory characteristics of the charge storage layer composed of Mo nanocrystals embedded in nonstoichiometry oxide (SiO(x)). X-ray photoelectron spectra analyses revealed that nitrogen was incorporated into the charge storage layer. Electric analyses indicated that the memory window was reduced and the retention and the endurance improved after the treatment. The reduction in the memory window and the improvement in retention were interpreted in terms of the nitrogen passivation of traps in the oxide around Mo nanocrystals. The robust endurance characteristic was attributed the improvement of the quality of the surrounding oxide by nitrogen passivation.
Size-dependent strain relaxation in InN islands grown on GaN by metalorganic chemical vapor deposition
(2009-02-09)
Tsai, Wen-Che
;
Lin, Feng-Yi
;
Ke, Wen-Cheng
;
Lu, Shu-Kai
;
Cheng, Shun-Jen
We report Raman measurements on InN islands grown on GaN by metalorganic chemical vapor deposition. The Raman frequency of the InN E(2) mode is found to decrease exponentially with the island's aspect ratio, indicating a size dependent strain relaxation during the island formation. Our results suggest that most of the strain at the InN-GaN interface have been released plastically during the initial stage of island formations. After that, the residual strain of only -3.5x10(-3) is further relaxed elastically via surface islanding. The experimental data are in agreement with the strain relaxation predicted from a simplified model analysis as well as three-dimensional finite-element simulations.
NiSiGe nanocrystals for nonvolatile memory devices
(2009-02-09)
Hu, Chih-Wei
;
Chang, Ting-
;
Tu, Chun-Hao
;
Chiang, Cheng-Neng
;
Lin, Chao-Cheng
In this work, charge-storage characteristics of NiSiGe nanocrystal memory device have been studied. Transmission electron microscope shows that the annealed NiSiGe film has higher nanocrystal size and density distribution. Related material analyses such as x-ray photoelectron spectroscopy, Raman spectroscopy, and energy dispersive spectrometer were used to confirm that the Ge elements provide the additional nucleation centers and enhance the nanocrystals aggregation during thermal process. With the improved nanocrystal formation process, a remarkable improvement of the memory effect is observed by comparing the NiSi and NiSiGe nanocrystals. In addition, the retention characteristics of the nanocrystals memory devices have been discussed.
New Host Containing Bipolar Carrier Transport Moiety for High-Efficiency Electrophosphorescence at Low Voltages
(2009-02-09)
Gao, Zhi Qiang
;
Luo, Meiming
;
Sun, Xiao Hua
;
Tam, Hoi Lam
;
Wong, Man Shing
A new host material for use in phosphorescent OLEDs with desirable electronic properties has been synthesized. The material exhibits superior carrier-transport properties, a narrow optical band gap, relatively high triplet energy, and high thermal stability. It is synthesized by integrating hole-transporting carbazole groups into an electron-transporting phenanthroline core (see figure), and is demonstrated to be an excellent host for phosphorescent dopant emitters.
Large vacuum Rabi splitting in ZnO-based hybrid microcavities observed at room temperature
(2009-02-09)
Chen, Jun-Rong
;
Lu, Tien-Chang
;
Wu, Yung-Chi
;
Lin, Shiang-Chi
;
Liu, Wei-Rein
Wide-band gap ZnO semiconductors are attractive materials for the investigation of microcavity exciton polaritons due to the large exciton binding energy and oscillator strength. We report the growth and characterization of bulk ZnO-based hybrid microcavity. The phenomenon of strong exciton-photon coupling at room temperature has been observed in the ZnO-based hybrid microcavity structure, which consists of 30 pair epitaxially grown AlN/AlGaN distributed Bragg reflector (DBR) on the bottom side of the 3/2 lambda thick ZnO cavity and 9 pair SiO(2)/HfO(2) DBR as the top mirror. The cavity quality factor is about 221. The experimental results show good agreement with theoretically calculated exciton-polariton dispersion curves based on transfer matrix method. From the theoretical and experimental exciton-polariton dispersion curves with two different cavity-exciton detuning values, the large vacuum Rabi splitting is estimated to be about 58 meV in the ZnO-based hybrid microcavity.
Lithium Ion Intercalation Performance of Porous Laminal Titanium Dioxides Synthesized by Sol-Gel Process
(2009-02-10)
Tsai, Min-Chiao
;
Chang, Jian-Chia
;
Sheu, Hwo-Shuenn
;
Chiu, Hsin-Tien
;
Lee, Chi-Young
We have synthesized novel mesoporous titanate nanosheets by reacting titanium isopropoxide (TTIP) with formic acid. The porous nanosheets were characterized as a new titanate structure with intercalation of formate groups and protons, in the form of HCOOH-intercalated titanate. Most interestingly, TiO(2)-B, a well-known but unusual titanium dioxide phase with great potential in applications in Li-ion batteries, was obtained after the nanosheets were heated above 250 degrees C. Mesoporous nanosheets of HCOOH-intercalated titanate, titanium dioxide with mostly TiO(2)-B and titanium dioxide with traces of TiO(2)-B were obtained by heating the as prepared mesoporous titanate nanosheets at 200, 300, and 550 degrees C, respectively. The method reported here is the first to utilize the sol-gel process to synthesize TiO(2)-B. In addition, different anodes were made from HCOOH-intercalated titanate and titanium dioxide with different ratios of TiO2-B to examine the performance of the charging/discharging capacity in Li ion intercalation. The discharging capacity of titanium dioxide with major TiO2-B can reach 357 mA h/g at the first charging cycle and is highest among TiO(2)-B reports so far.
Different effects of probiotic species/strains on infections in preschool children: A double-blind, randomized, controlled study
(2009-02-11)
Lin, Jun-Song
;
Chiu, Yi-Han
;
Lin, Nien-Tsung
;
Chu, Chia-Hsiang
;
Huang, Kuo-Chin
Treatment and prevention of pediatric infectious diseases of three commercial probiotic products were evaluated by a double-blind, randomized, controlled trial. Test subjects under age 5,1062 in total, were distributed randomly into four groups. This investigation showed that L. casei rhamnosus can control bacterial, viral and respiratory infections; a multi-species probiotic reduced gastrointestinal disease significantly. Long-term consumption of L. rhamnosus T cell-1 decreased the incidence of bacterial infection. (C) 2008 Elsevier Ltd. All rights reserved.
Single-electron effects in non-overlapped multiple-gate silicon-on-insulator metal-oxide-semiconductor field-effect transistors
(2009-02-11)
Lee, W.
;
Su, P.
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper systematically presents controlled single-electron effects in multiple- gate silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) with various gate lengths, fin widths, gate bias and temperature. Our study indicates that using the non-overlapped gate to source/drain structure as an approach to the single-electron transistor (SET) in MOSFETs is promising. Combining the advantage of gate control and the constriction of high source/drain resistances, single-electron effects are further enhanced using the multiple- gate architecture. From the presented results, downsizing multiple- gate SOI MOSFETs is needed for future room-temperature SET applications. Besides, the tunnel barriers and access resistances may need to be further optimized. Since the Coulomb blockade oscillation can be achieved in state-of-the-art complementary metal-oxide-semiconductor (CMOS) devices, it is beneficial to build SETs in low-power CMOS circuits for ultra-high-density purposes.
Highest Urgency First (HUF): A latency and modulation aware bandwidth allocation algorithm for WiMAX base stations
(2009-02-12)
Lin, Yi-Neng
;
Lin, Ying-Dar
;
Lai, Yuan-Cheng
;
Wu, Che-Wen
;
交大名義發表
The mobile WiMAX systems based on IEEE 802.16e-2005 provide high data rate for mobile wireless networks. However, the link quality is frequently unstable owing to mobility and air interference and therefore impacts the latency requirement of real-time applications. In the WiMAX standard, the modulation/coding scheme and the boundary of uplink/downlink sub-frames could be adjusted subject to channel quality and the traffic volume, respectively. This provides us a chance to design a MAC-layer uplink/downlink bandwidth allocation algorithm that is QoS/PHY-aware. This work takes into account the adaptive modulation and coding scheme (MCS), uplink and downlink traffic volume, and QoS parameters of all five defined service classes to design a bandwidth allocation algorithm that calculates the slot allocation in two phases. The first phase decides the boundary of uplink and downlink sub-frames by satisfying requests with pending latency violation and proportionating according to traffic volume, while the second phase allocates slots to mobile stations considering urgency, priority and fairness. Simulation results show our algorithm achieves zero latency violation and higher system throughput compared to existing non-QoS/PHY-aware or less-QOS/PHY-aware approaches. (C) 2008 Elsevier B.V. All rights reserved.