Browsing by Author "Chou, Hsiang-Yu"

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Anticorrelation between the splitting and polarization of the exciton fine structure in single self-assembled InAs/GaAs quantum dots
(2011-02-28)
Lin, Chia-Hsien
;
You, Wen-Ting
;
Chou, Hsiang-Yu
;
Cheng, Shun-Jen
;
Lin, Sheng-Di
We report on a systematic correlation between the fine-structure splitting and polarization anisotropy of excitons in InAs/GaAs quantum dots, but with an unexpected reversal in order of the polarization eigenaxes. Such an anticorrelation is explained by a large valence-band-mixing induced splitting due to the shape and strain anisotropies. The strength and phase of valence band mixing are also found to play an important role in the tuning of fine structure splitting using an in-plane magnetic field.
Efficient Heat Dissipation of Photonic Crystal Microcavity by Mono layer Graphene
(2013-12-01)
Shih, Min-Hsiung
;
Li, Lain-Jong
;
Yang, Yi-Chun
;
Chou, Hsiang-Yu
;
Lin, Cheng-Te
Graphene, which exhibits excellent thermal conductivity, is a potential heat dissipation medium for compact optoelectronic devices. Photonic devices normally produce large-quantity of unwanted heat, and thus, a heat dissipation strategy is urgently needed. In this study, single-layer graphene (SLG) grown by chemical vapor deposition (CVD) is used to cover the surface of a photonic crystal (PhC) cavity, where the heat flux produced by the PhC cavity can be efficiently dissipated along the in-plane direction of the SLG. The thermal properties of the graphene-capped PhC cavity were characterized by experiments and theoretical calculations. The thermal resistance of the SLG-capped PhC cavity obtained from experiments is lower than half of that of a bare PhC cavity. The temperature of a SLG-capped PhC cavity is 45 K lower than that without SLG capping under an optical power of 100 mu W. Our simulation results indicate that SLG receives the majority of the heat fluxes from the device, leading to the efficient heat dissipation. Both the experimental and simulation results suggest that the SLG is a promising material to enhance the heat dissipation efficiency for optoelectronic applications.