Browsing by Author "Wang, C. H."

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10 Gb/s TDM passive optical networks using four wavelengths multiplexed channels
(2009-07-01)
Wang, C. H.
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Shih, F. Y.
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Yeh, C. H.
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Chow, C. W.
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Chi, S.
We propose a new architecture for 10 Gb/s upstream traffic in TDM-PON using externally injection-locked Fabry-Perot laser diodes (FP-LDs) in each optical network unit (ONU). Four directly modulated 2.5 Gb/s FP-LDs were injection-locked by continuous wave (CW) carriers distributed from the optical line terminal (OLT). Hence, a total of 10 Gb/s upstream traffic can be achieved. Experimental results show negligible power penalty at a transmission of 25 km standard single mode fiber (SMF) without dispersion compensation. The performance of the injection-locked FP-LD is also studied. (C) 2009 Elsevier B.V. All rights reserved.
10 Gb/s Uplink Traffic Transmitter Using External Optical Injection for TDM Passive Optical Networks
(2009)
Wang, C. H.
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Shih, F. Y.
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Yeh, C. H.
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Chow, C. W.
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Chi, S.
We propose and demonstrate an upgrade solution for 10-Gb/s TDM-PON using four directly-modulated 2.5-Gb/s FP-LDs in each ONU. The performance of the proposed scheme is analyzed, showing its feasibility for the next-generation 10-Gb/s networks. (C) 2009 Optical Society of America
100 GHz ultra-wideband (UWB) fiber-to-the-antenna (FTTA) system for in-building and in-home networks
(2010-01-18)
Chow, C. W.
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Kuo, F. M.
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Shi, J. W.
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Yeh, C. H.
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Wu, Y. F.
Fiber-to-the-antenna (FTTA) system can be a cost-effective technique for distributing high frequency signals from the head-end office to a number of remote antenna units via passive optical splitter and propagating through low-loss and low-cost optical fibers. Here, we experimentally demonstrate an optical ultra-wideband (UWB) - impulse radio (IR) FTTA system for in-building and in-home applications. The optical UWB-IR wireless link is operated in the W-band (75 GHz - 110 GHz) using our developed near-ballistic unitraveling-carrier photodiode based photonic transmitter (PT) and a 10 GHz mode-locked laser. 2.5 Gb/s UWB-IR FTTA systems with 1,024 high split-ratio and transmission over 300 m optical fiber are demonstrated using direct PT modulation. (C) 2010 Optical Society of America
A high precision calibration of the nonlinear energy response at Daya Bay
(2019-10-01)
Adey, D.
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An, F. P.
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Balantekin, A. B.
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Band, H. R.
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Bishai, M.
A high precision calibration of the nonlinearity in the energy response of the Daya Bay Reactor Neutrino Experiment's antineutrino detectors is presented in detail. The energy nonlinearity originates from the particle-dependent light yield of the scintillator and charge-dependent electronics response. The nonlinearity model is constrained by.. calibration points from deployed and naturally occurring radioactive sources, the.. spectrum from B-12 decays, and a direct measurement of the electronics nonlinearity with a new flash analog-to-digital converter readout system. Less than 0.5% uncertainty in the energy nonlinearity calibration is achieved for positrons of kinetic energies greater than 1 MeV.
A novel approach to conduct risk analysis of FMEA for PCB fabrication process
(2011)
Wang, C. H.
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工業工程與管理學系
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Department of Industrial Engineering and Management
Failure mode and effects analysis (FMEA) has been widely applied to many industries to identify potential deteriorated problems for product design or process fabrication. Generally, the conventional FMEA prioritizes specific failure modes based on a so-called risk priority number (i.e., RPN=O*D*S), which is simply a mathematical product of three risk factors: occurrence (O), detection (D), and severity (S). Obviously, there exist several flaws for the conventional FMEA: (1) the relative importance among three risk factors is neglected, and (2) failure modes caused by different combinations of three risk factors are possible to generate the same RPN and hence the identification of their root causes becomes quite difficult in practice. As a result, a fuzzy multi-criteria decision making (MCDM) based framework that incorporates fuzzy entropy and fuzzy TOPSIS (technique for order preference by similarity to ideal solution) is presented to improve the conventional FMEA. An industrial example regarding the manufacturing process of PCB (printed circuit board) is demonstrated in this study.
A self-protected colorless WDM-PON with 2.5 Gb/s upstream signal based on RSOA
(2008-08-04)
Yeh, C. H.
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Chow, C. W.
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Wang, C. H.
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Shih, F. Y.
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Chien, H. C.
In this investigation, we propose and demonstrate a colorless wavelength division multiplexed passive optical network (WDM-PON) at 2.5 Gb/s using reflective semiconductor optical amplifier (RSOA)-based optical networking units (ONUs); together with a self-protected architecture against fiber fault. In the optical line terminal (OLT), we use an array of self-seeding Fabry-Perot laser diodes (FP-LDs) to provide single-longitudinal-mode (SLM) continuous wave (CW) optical sources for the external injection to the RSOA-based ONUs. The self-survivable function for protecting the fiber fault in the distributed fibers and the proposed network performance are investigated and discussed. (C) 2008 Optical Society of America.
A side-by-side comparison of Daya Bay antineutrino detectors
(1970-01-01)
An, F. P.
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An, Q.
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Bai, J. Z.
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Balantekin, A. B.
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Band, H. R.
"The Daya Bay Reactor Neutrino Experiment is designed to determine precisely the neutrino mixing angle theta(13) with a sensitivity better than 0.01 in the parameter sin(2) 2 theta(13) at the 90% confidence level. To achieve this goal, the collaboration will build eight functionally identical antineutrino detectors. The first two detectors have been constructed, installed and commissioned in Experimental Hall 1, with steady data-taking beginning September 23, 2011. A comparison of the data collected over the subsequent three months indicates that the detectors are functionally identical, and that detector-related systematic uncertainties are smaller than requirements. (C) 2012 Elsevier B.V. All rights reserved."
A Strain-Driven Morphotropic Phase Boundary in BiFeO(3)
(2009-11-13)
Zeches, R. J.
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Rossell, M. D.
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Zhang, J. X.
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Hatt, A. J.
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He, Q.
Piezoelectric materials, which convert mechanical to electrical energy and vice versa, are typically characterized by the intimate coexistence of two phases across a morphotropic phase boundary. Electrically switching one to the other yields large electromechanical coupling coefficients. Driven by global environmental concerns, there is currently a strong push to discover practical lead-free piezoelectrics for device engineering. Using a combination of epitaxial growth techniques in conjunction with theoretical approaches, we show the formation of a morphotropic phase boundary through epitaxial constraint in lead-free piezoelectric bismuth ferrite (BiFeO(3)) films. Electric field-dependent studies show that a tetragonal-like phase can be reversibly converted into a rhombohedral-like phase, accompanied by measurable displacements of the surface, making this new lead-free system of interest for probe-based data storage and actuator applications.
A Strain-Driven Morphotropic Phase Boundary in BiFeO3
(2009-11-13)
Zeches, R. J.
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Rossell, M. D.
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Zhang, J. X.
;
Hatt, A. J.
;
He, Q.
Piezoelectric materials, which convert mechanical to electrical energy and vice versa, are typically characterized by the intimate coexistence of two phases across a morphotropic phase boundary. Electrically switching one to the other yields large electromechanical coupling coefficients. Driven by global environmental concerns, there is currently a strong push to discover practical lead-free piezoelectrics for device engineering. Using a combination of epitaxial growth techniques in conjunction with theoretical approaches, we show the formation of a morphotropic phase boundary through epitaxial constraint in lead-free piezoelectric bismuth ferrite (BiFeO3) films. Electric field-dependent studies show that a tetragonal-like phase can be reversibly converted into a rhombohedral-like phase, accompanied by measurable displacements of the surface, making this new lead-free system of interest for probe-based data storage and actuator applications.
An apparatus for studying spallation neutrons in the Aberdeen Tunnel laboratory
(2013-09-21)
Blyth, S. C.
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Chan, Y. L.
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Chen, X. C.
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Ch, M. C.
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Hahn, R. L.
In this paper, we describe the design, construction and performance of an apparatus installed in the Aberdeen Tunnel laboratory in Hong Kong for studying spallation neutrons induced by cosmic-ray muons under a vertical rock overburden of 611 m water equivalent (m.w.e.). The apparatus comprises six horizontal layers of plastic-scintillator hodoscopes for determining the direction and position of the incident cosmic-ray muons. Sandwiched between the hodoscope planes is a neutron detector filled with 650 kg of liquid scintillator doped with about 0.06% of Gadolinium by weight for improving the efficiency of detecting the spallation neutrons. Performance of the apparatus is also presented. (C) 2013 Elsevier B.V. All rights reserved.
Analysis of the carrier-suppressed single-sideband modulators used to mitigate Rayleigh backscattering in carrier-distributed PON
(2011-05-23)
Chow, C. W.
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Wang, C. H.
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Yeh, C. H.
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Chi, S.
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光電工程學系
By using the carrier-suppressed single-sideband (CS-SSB) modulation, the Rayleigh backscattering (RB) experienced by the uplink signal can be effectively mitigated due to the reduction of the spectral overlap between the uplink signal and the distributed optical carrier. In this work, we first introduce the theoretical analysis of the CS-SSB generation using the dual-drive MZM (DD-MZM)-based and a dual-parallel MZM (DP-MZM)-based optical networking units (ONUs). Due to the different modulation mechanisms of the two CS-SSB modulations, the frequency components of the generated CS-SSB signals are also different. The transmission performance and the dispersion tolerance of the uplink signals generated by the two CS-SSB modulators are also analyzed and discussed. (C) 2011 Optical Society of America
Bidirectional ROF Transmission and Signal Remodulation Using Separate Optical Clock Distribution to Mitigate Signal Distortions
(2009)
Chow, C. W.
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Xu, L.
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Yeh, C. H.
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Wang, C. H.
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Shih, F. Y.
We demonstrate a bidirectional ROF system using a separate optical-clock distribution to mitigate signal-fading and code time-shifting. Error-free signal remodulation using downlink DPSK and uplink OOK was achieved in a 20-km reach ROF system. (C)2009 Optical Society of America
Carrier Distributed PON Using SSB-CS Signal for Rayleigh Backscattering Suppression
(2010)
Chow, C. W.
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Yeh, C. H.
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Liu, Y. F.
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Wang, C. H.
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Wu, C. L.
We demonstrate using single-sideband-carrier-suppressed (SSB-CS) signal to suppress the Rayleigh-Backscattering (RB) in a carrier-distributed PON. The SSB signal is generated by a dual-parallel Mach-Zehnder modulator (DP-MZM). The split-ratio and reach are also investigated and analyzed.
Characteristics of efficiency droop in GaN-based light emitting diodes with an insertion layer between the multiple quantum wells and n-GaN layer
(2010-12-20)
Chang, S. P.
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Wang, C. H.
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Chiu, C. H.
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Li, J. C.
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Lu, Y. S.
We have studied the characteristics of efficiency droop in GaN-based light emitting diodes (LEDs) with different kinds of insertion layers (ILs) between the multiple quantum wells (MQWs) layer and n-GaN layer. By using low-temperature (LT) (780 degrees C) n-GaN as IL, the efficiency droop behavior can be alleviated from 54% in reference LED to 36% from the maximum value at low injection current to 200 mA, which is much smaller than that of 49% in LED with InGaN/GaN short-period superlattices layer. The polarization field in MQWs is found to be smallest in LED with InGaN/GaN SPS layer. However, the V-shape defect density, about 5.3 x 10(8) cm(-2), in its MQWs region is much higher than that value of 2.9 x 108 cm(-2) in LED with LT n-GaN layer, which will lead to higher defect-related tunneling leakage of carriers. Therefore, we can mainly assign this alleviation of efficiency droop to the reduction of dislocation density in MQWs region rather than the decrease of polarization field. (C) 2010 American Institute of Physics. [doi:10.1063/1.3531957]
Characterization of Dark-Return-to-Zero Modulation Format at Different Transmitter and Receiver Bandwidths
(2008)
Wang, C. H.
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Chow, C. W.
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Yeh, C. H.
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Chi, S.
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光電工程學系
This work characterizes how the bandwidths of transmitter, receiver and optical filter affecting the quality of optical dark-return-to-zero (DRZ) signal. Optimum filtering bandwidths at Back-to-back (B2B) and 80km single mode fiber transmission are analyzed.
Characterization of Rayleigh backscattering performance of CS-SSB signal in carrier distributed passive optical network
(2011-06-15)
Wang, C. H.
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Yeh, C. H.
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Chow, C. W.
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Wu, Y. F.
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Shih, F. Y.
Rayleigh backscattering (RB) is an intrinsic phenomenon when light propagating in fiber and its level is fixed by the fiber type and the network configuration used. Thus. RB noise would be one of the major impairments in a carrier distributed passive optical network (PON). Previously demonstrated carrier suppressed subcarrier-amplitude modulated phase shift keying (CSS-AMPSK) modulation may be useful to effectively mitigate the RB noise. However, this modulation is basically a carrier suppressed double sidebands modulation (CS-DSB) format, in which the same information is carried by the two sidebands with equal magnitude. This is not very power-efficient for PON. Here, we further extend our RB studies by using carrier suppressed single sideband non-return-to-zero (CS-SSB-NRZ) modulation. We experimentally characterize the CS-SSB-NRZ modulation when subjected to both contributions of RB: Carrier-RB and Signal-RB. Then, numerical simulations are performed, and the results are in good match with the experiment. Finally, upstream transmission experiment is performed showing the feasibility of using the CS-SSB-NRZ signal for the carrier distributed PON. The RB performance of the SSB-NRZ signals transmitted at different distances and driven at different radio-frequency (RF) f(s) is also investigated. (C) 2011 Elsevier B.V. All rights reserved.
Comparison of Two CS-SSB Modulators Used in Bidirectional Carrier Distributed Long-Reach Passive Optical Network
(2011)
Wang, C. H.
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Yang, L. G.
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Chow, C. W.
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Yeh, C. H.
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Chi, S.
Two different CS-SSB modulators based on Mach-Zehnder structure used in carrier-distributed long-reach passive optical networks are investigated and compared. The Rayleigh-backscattering beat noise tolerance and transmission performance are also discussed. (C) 2011 Optical Society of America
Cosmogenic neutron production at Daya Bay
(2018-03-26)
An, F. P.
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Balantekin, A. B.
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Band, H. R.
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Bishai, M.
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Blyth, S.
Neutrons produced by cosmic ray muons are an important background for underground experiments studying neutrino oscillations, neutrinoless double beta decay, dark matter, and other rare-event signals. A measurement of the neutron yield in the three different experimental halls of the Daya Bay Reactor Neutrino Experiment at varying depth is reported. The neutron yield in Daya Bay's liquid scintillator is measured to be Y-n = (10.26 +/- 0.86) x 10(-5), (10.22 +/- 0.87) x 10(-5), and (17.03 +/- 1.22) x 10(-5) mu(-1)g(-1)cm(2) at depths of 250, 265, and 860 meters-water-equivalent. These results are compared to other measurements and the simulated neutron yield in FLUKA and GEANT4. A global fit including the Daya Bay measurements yields a power law coefficient of 0.77 +/- 0.03 for the dependence of the neutron yield on muon energy.
Demonstration of High Spectral Efficient OFDM-QAM Long Reach Passive Optical Network
(2008)
Chow, C. W.
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Yeh, C. H.
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Wang, C. H.
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Shih, F. Y.
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Lin, Y. M.
We demonstrate a high spectral-efficient LR-PON using 4Gb/s OFDM-QAM for both up-and-downstream, achieving a high split-ratio 256, using optical components optimized for GPON.
Demonstration of Signal Remodulation Long Reach Carrier Distributed Passive Optical Network using OFDM-QAM Signal
(2009)
Chow, C. W.
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Yeh, C. H.
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Wang, C. H.
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Shih, F. Y.
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Chi, S.
OFDM is a promising candidate for LR-PON. We study the possibility of using OFDM for signal remodulation in the LR-PON. Three different colorless ONU architectures are tested and compared.