Browsing by Author "Lin, K. F."

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Novel chirped multilayer quantum-dot lasers
(2008-01-01)
Lin, G.
;
Chang, C. Y.
;
Tseng, W. C.
;
Lee, C. P.
;
Lin, K. F.
Chirped multilayer (N=10) QD lasers with 2-, 3- and 5-layer of longer-, medium-, and shorter-wavelength QD stacks, respectively, were grown in this work. Low threshold current density and high saturated modal gain were achieved in this specially designed QD structure. Empirical gain-current analysis was performed on this chirped multilayer QD structure for the first time. It was consistent with our spectral observations and provided valuable information on carrier recombination in chirped multilayer QD structure. Two novel spectral characteristics were discovered also for the first time. First, simultaneous two-wavelength lasing around threshold was observed under particular gain-loss condition at this specific multilayer structure of QD stacking numbers. Second, at cryogenic temperature, simultaneous two-wavelength lasing emissions switched from longer-wavelength lasing first to shorter-wavelength lasing first with increasing current injection. Non-uniform carrier distribution among chirped multilayer QD structure is evident at low temperature below 200 K from our analysis.
Novel chirped multilayer quantum-dot lasers - art. no. 69970R
(2008)
Lin, G.
;
Chang, C. Y.
;
Tseng, W. C.
;
Lee, C. P.
;
Lin, K. F.
Chirped multilayer (N=10) QD lasers with 2-, 3- and 5-layer of longer-, medium-, and shorter-wavelength QD stacks, respectively, were grown in this work. Low threshold current density and high saturated modal gain were achieved in this specially designed QD structure. Empirical gain-current analysis was performed on this chirped multilayer QD structure for the first time. It was consistent with our spectral observations and provided valuable information on carrier recombination in chirped multilayer QD structure. Two novel spectral characteristics were discovered also for the first time. First, simultaneous two-wavelength lasing around threshold was observed under particular gain-loss condition at this specific multilayer structure of QD stacking numbers. Second, at cryogenic temperature, simultaneous two-wavelength lasing emissions switched from longer-wavelength lasing first to shorter-wavelength lasing first with increasing current injection. Non-uniform carrier distribution among chirped multilayer QD structure is evident at low temperature below 200 K from our analysis.
Size dependence of the electronic structures and electron-phonon coupling in ZnO quantum dots
(2007-12-24)
Ray, S. C.
;
Low, Y.
;
Tsai, H. M.
;
Pao, C. W.
;
Chiou, J. W.
The electronic structures and optical properties of various sizes of ZnO quantum dots (QDs) were studied using x-ray absorption, photoluminescence, and Raman spectroscopy. The increase in the intensity ratio of the second-order Raman spectra of longitudinal optical mode and its fundamental mode, which is related to the strength of the electron-phonon coupling (EPC), is found to increase with the size of QD. The trend of EPC also correlates with the increase of the intensity ratio of the O 2p(pi) (I(pi)) and 2p(sigma) (I(sigma)) orbital features in the O K-edge x-ray absorption near-edge structure (XANES) as the size of QD increases. The EPC and XANES results suggest that the crystal orientations of ZnO QDs are approximately aligned with the c axis parallel with the polarization of x-ray photons. (c) 2007 American Institute of Physics.
Tunable optical group delay in quantum dot vertical-cavity surface-emitting laser at 10 GHz
(2006-08-31)
Peng, P. C.
;
Lin, C. T.
;
Kuo, H. C.
;
Lin, G.
;
Tsai, W. K.
This investigation experimentally demonstrates tunable optical group delay in a 1.3 mu m quantum dot vertical-cavity surface-emitting laser (QD VCSEL). The QD VCSEL is fabricated on a GaAs substrate. Tunable delays are achieved by varying the bias currents, and the maximum delay of 42 ps at 10 GHz has been demonstrated at room temperature.
Tunable slow light device using quantum dot semiconductor laser
(2006-12-25)
Peng, P. C.
;
Lin, C. T.
;
Kuo, H. C.
;
Tsai, W. K.
;
Liu, J. N.
This investigation experimentally demonstrates a tunable slow light device using a quantum dot (QD) semiconductor laser. The QD semiconductor laser at 1.3 mu m fabricated on a GaAs substrate is grown by molecular beam epitaxy. Tunable slow light can be achieved by adjusting the bias current and wavelength detuning. The slow light device operated under probe signal from 5 to 10 GHz is presented. Moreover, we also demonstrate that the tunable slow light device can be used in a subcarrier multiplexed system. (C) 2006 Optical Society of America.