Browsing by Author "CHEN, HM"

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DECISION-PROCESSES AND INFORMATION
(1989)
TARNG, MY
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CHEN, HM
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管理科學系
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Department of Management Science
INSTABILITY IN SURFACE EMITTING LASERS DUE TO EXTERNAL OPTICAL FEEDBACK
(1993-01-01)
CHEN, HM
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TAI, K
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HUANG, KF
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KAO, YH
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WYNN, JD
Instability in the output of dc-biased surface emitting lasers due to an external cavity effect was observed. The output power spectrum exhibited multiple peaks with spacing corresponding to exactly the round-trip delay in silica fibers with length ranging from 2 m to 2 km. The magnitude of the peaks was enhanced in the spectral region centered at the laser relaxation frequency. With increased feedback, the background of the output spectrum was found to increase, indicating the presence of optical chaos. Numerical simulation based on the rate equation analysis was found to agree with the experiment, indicating the surface emitting lasers are well described by the rate equation and are susceptible to feedback as the edge emitting lasers.
INTERACTIONS BETWEEN AL-1 WT-PERCENT SI THIN-FILM AND W-TI BARRIER LAYER
(1994-05-15)
CHANG, PH
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CHEN, HM
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LIU, HY
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BOHLMAN, JG
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材料科學與工程學系
The interaction of Al-1 wt% Si with a W-Ti barrier layer in the Al/Ti3W7/SiO2/Si system was studied over the temperature range of 400-500-degrees-C for reaction times up to 300 h. The interaction was found to be diffusion-controlled, and to occur in a layer-by-layer fashion. The first reaction product is always Al12W, which forms at the Al/Ti3W7 interface. With excess W in the system, Al will eventually be completely converted to Al12W, and further interactions result in the formation of an Al4W layer at the Al12W/Ti3W7 interface. The amount of Al4W increases at the expense of Al12W. Ti plays a minor role in the interaction and forms a small amount of Al3Ti precipitates in the Al12W matrix. Decomposition of the Ti3W7 pseudoalloy into W and Ti phases is not significant, and is not detected by X-ray diffraction even after annealing at 500-degrees-C for 300 h. The kinetics of the Al12W formation follows a parabolic reaction law with an activation energy of 2.53 eV. The sheet resistance of the film is insensitive to compound formation as long as a continuous Al film exists in the system. The sheet resistance increases dramatically when Al is consumed to the extent that it is no longer a continuous film. The sheet resistance of the Al12W layer is estimated to be 570 mOMEGA square-1.
MODE DESCRIPTION OF ROUTES TO CHAOS IN EXTERNAL-CAVITY COUPLED SEMICONDUCTOR-LASERS
(1994-08-01)
KAO, YH
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WANG, NM
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CHEN, HM
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電信工程研究所
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電信研究中心
The nonlinear behaviors of routes to chaos in semiconductor lasers with external optical feedback were explored in this work. It was indicated that the relaxation oscillation was the origin of the first nonlinear instability of optical intensity under a short delay. Three types of transition routes with quasi-periodic, subharmonic oscillation, and periodic doubling to optical chaos were distinguished in terms of the delay time normalized to the inverse of the relaxation oscillation frequency of a solitary laser diode. The linearized mode theory and small-signal response were confirmed as part of the phenomena in the transitions to chaos.
THE EFFECT OF SI AND CU ON THE INTERACTIONS BETWEEN AL FILMS AND A TIW BARRIER LAYER
(1992-10-01)
CHANG, PH
;
CHEN, HM
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LIU, HY
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材料科學與工程學系
;
Department of Materials Science and Engineering
The effect of doping 1 wt % Si or 0.9 wt % Cu to Al films on the interactions between Al and TiW barrier layers at 450-degrees-C was studied. It was found that the first product is always Al12W, which forms at the Al/TiW interface, irrespective of the dopant addition. However, doping 1 wt % Si to Al film enhances the Al12W formation while doping 0.9 wt % Cu retards its formation. With excess tungsten in the system, Al12W would further react with W to form Al/W compounds with higher W content. In pure Al film, both the hexagonal Al5W phase and the monoclinic Al4W phase were detected to form after prolonged annealing at 450-degrees-C. The addition of 1 wt % Si or 0.9 wt % Cu to Al prohibits the formation of Al5W, thus only the Al4W phase was observed at the W/Al12W interface in the doped Al films.