Browsing by Author "Chao, C. H."

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Anisotropy light extraction with high polarization ratio from photonic crystal fight-emitting diodes
(2008)
Lai, Chun-Feng
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Kuo, Hao-Chung
;
Lu, Tien-Chang
;
Wang, Shing-Chang
;
Chao, C. H.
The azimuthal anisotropy of GaN photonic crystal light-emitting diode is investigated using an annular structure. The extracted light distribution has P/S ratio of 5.5 for fight propagating in Gamma X direction and 2.1 for Gamma M direction. @2007 Optical Society of America
Anisotropy of light extraction from two-dimensional photonic crystal light-emitting diodes
(2007-09-17)
Lai, Chun-Feng
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Kuo, H. C.
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Chao, C. H.
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Hsueh, H. T.
;
Wang, J.-F. T.
Anisotropic light extraction of photonic crystal (PhC) light-emitting diodes in the azimuthal direction has been investigated with an annular structure of triangular PhC lattice. The optical images of the photoluminescence light extraction are obtained with laser excitation. For increasing lattice constant, sixfold symmetric patterns with varying numbers of petals in multiples of six are observed and analyzed. A map of the anisotropy for various lattice constants and numerical apertures is constructed. Several features of light propagations associated with the PhC are observed including the focusing and collimating behaviors.(c) 2007 American Institute of Physics.
Azimuthal anisotropy of light extraction from photonic crystal light-emitting diodes
(2008)
Lai, Chun-Feng
;
Kuo, H. C.
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Chao, C. H.
;
Hsueh, H. T.
;
Wang, J. -F. T.
Photonic crystal (PhC) light-emitting diodes (LEDs) exhibiting anisotropic light extraction have been investigated experimentally and theoretically. It is found that the anisotropic light extraction strongly depends on the lattice constant and orientation. Optical images of the anisotropy in the azimuthal direction are obtained using annular structure with triangular lattice. 6-fold symmetric light extraction patterns with varying number of petals are observed. More petals in multiple of 6 appear in the observed image with lattice constant increasing. This anisotropic behavior suggests a new means to optimize the PhC design of GaN LED for light extraction.
Azimuthal anisotropy of light extraction from photonic crystal light-emitting diodes
(2007)
Hsuch, H. T.
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Wang, J. -F. T.
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Chao, C. H.
;
Yeh, W. Y.
;
Chi, J. Y.
Photonic crystal light-emitting diodes exhibiting anisotropic light extraction efficiency have been investigated experimentally and theoretically. Images of the anisotropy in the azimuthal direction are obtained using annular structures with triangular lattice. Depending on the lattice constants, 6-fold symmetric patterns with varying number of petals are obtained.
Enhanced vertical extraction efficiency from a thin-film InGaN-GaN light-emitting diode using a 2-D photonic crystal and an omnidirectional reflector
(2008-05-01)
Lin, C. H.
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Yen, H. H.
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Lai, C. F.
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Huang, H. W.
;
Chao, C. H.
An InGaN-GaN thin-film vertical-type light-emitting diode with a two-dimensional photonic crystal (PC) on the emitting surface and a TiO2-SiO2 onmidirectional reflector on the bottom was fabricated. The device was investigated by performing a series of experiments and numerical computations. Electroluminescence measurement revealed a strong extraction enhancement in the vertical direction at 433-nm wavelength. The emission spectrum of the light was found to be strongly modified by the PC to have a significantly narrow linewidth of 5 nm. Our experimental results were in accord with those obtained from our numerical findings.
Hole shape effect of photonic crystals on the guided resonance modes in GaN-based ultra-thin film-transferred light-emitting diodes
(2010)
Lai, C. F.
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Chao, C. H.
;
Kuo, H. C.
;
Yu, P.
;
Yeh, W. Y.
The guided resonance mode affected the different hole shapes of photonic crystals in GaN ultra-thin film-transferred light-emitting diodes. The ellipse-hole PhC extracted a fewer modes than the regular PhC due to the lattice symmetry break. @2010 Optical Society of America