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Your search keyword '"Chang, Allan S.P."' showing total 6 results
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6 results on '"Chang, Allan S.P."'

3. Design of optical path for wide-angle gradient-index antireflection coatings

Author

Chen, Minfeng, Chang, Hung-chun, Chang, Allan S.P., Lin, Shawn-Yu, Xi, J.-Q., and Schubert, E.F.

Subjects
Coatings -- Optical properties, Coatings -- Design and construction, Reflection (Optics) -- Control, Wavelength -- Observations, Refraction -- Control, Astronomy, Physics
Abstract

What we believe to be a new principle is introduced for the design and selection of gradient-index antireflection profiles that are effective over a wide range of incident angles as well as wavelengths at a given physical film thickness. It is shown that at oblique incidence the smoothness of the optical path of incident light inside a gradient-index film has a crucial effect on the overall reflection. Thus the smoothness of variations in refractive angle (rather than that of the index profile itself) needs to be maximized for wide-angle operation. As an example, the performance of Gaussian and Quintic profiles at large incident angles are considered in light of this point of view. OCIS codes: 310.1210, 310.1620.

Published
2007

4. Analysis of photon recycling using metallic photonic crystal

Author

Yong-Sung Kim, Chang, Allan S.P., and Kai-Ming Ho

Subjects
Photons -- Properties, Infrared radiation -- Analysis, Silver compounds -- Optical properties, Energy efficiency -- Research, Physics
Abstract

A photon recycling scheme is examined using two-dimensional metallic photonic crystals made of silver in order to improve energy efficiency of an incandescent light source. Results show that photon-recycled incandescent light source using metallic photonic crystals is a feasible alternative future lighting solution.

Published
2007

6. Simultaneously enhancing internal and extraction efficiencies of GaN-based light emitting diodes via chemical-wet-etching patterned-sapphire-substrate (CWE-PSS)

Author

Lee, Yaju, Chiu, Chinhua, Kuo, Haochung, Lu, Tien-Chang, Wang, Shingchung, Ng, Kar Wai, Lau, Kei May, Yang, Zupo, Chang, Allan S.P., Lin, Shawnyu, Lee, Yaju, Chiu, Chinhua, Kuo, Haochung, Lu, Tien-Chang, Wang, Shingchung, Ng, Kar Wai, Lau, Kei May, Yang, Zupo, Chang, Allan S.P., and Lin, Shawnyu

Abstract

We report a chemical-wet-etching patterned-sapphire-substrate (CWE-PSS) that simultaneously enhances internal quantum efficiency and light extraction efficiency of gallium nitride based light-emitting-diode (LED). According to transmission electron microscopy (TEM) images, the threading dislocations penetrating into active region was dramatically reduced in the CWE-PSS structure compared to the planar sapphire substrate, i.e. enhancement of internal quantum efficiency. And according to the measurement of angular dependent diffraction power, CWE-PSS also serves as a diffraction grating which diffracts guided light into escaping cones, further improving ligh: extraction efficiency of LED device. © The Electrochemical Society.

Published
2007

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