Browsing by Author "Hsieh, W. -F."

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Q-switched and mode-locked pulses generation in Nd : GdVO4 laser with dual loss-modulation mechanism
(2008-04-01)
Lin, J. -H.
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Lin, K. -H.
;
Hsu, H. -H.
;
Hsieh, W. -F.
;
光電工程學系
Regular and robust Q-switched and mode-locked (QML) pulses are produced in Nd:GdVO4 laser by the integration of nonlinear mirror and semiconductor saturable absorber mirror. The threshold of QML operation is increased by putting the SESAM in laser cavity with large beam radius. The nonlinear mirror absorber can further increase nonlinear loss modulation of pulses to produce the stable and periodic QML pulses.
Tight-binding theory for coupled photonic crystal waveguides
(2007-03-01)
Chien, F. S. -S
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Tu, J. B.
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Hsieh, W. -F.
;
Cheng, S. -C.
;
光電工程學系
The point-defect coupling under the tight-binding approximation is introduced to describe the behavior of dispersion relations of the guided modes in a single photonic crystal waveguide (PCW) and two coupled identical PCWs. The cross-coupling coefficient beta of a point defect in one PCW to the nearest-neighboring (NN) defect in the other PCW causes the split of the dispersion curves, whereas the cross-coupling coefficient gamma to the next-NN defects causes a sinusoidal modulation to the dispersion curves. Furthermore, the sign of beta determines the parities of the fundamental guided modes, which can be either even or odd, and the inequality parallel to beta parallel to