Browsing by Author "Chen, Yi-Jiun"

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AlGaInP Red LEDs with Hollow Hemispherical Polystyrene Arrays
(2018-01-17)
Cheng, Wen-Ching
;
Huang, Shih-Yung
;
Chen, Yi-Jiun
;
Wang, Chia-Sheng
;
Lin, Hoang Yan
A hollow hemispherical polystyrene (HHPS) was fabricated to reduce total internal reflection in AlGaInP-based LEDs. At an injection current of 350 mA, the external quantum efficiencies of LED-I, LED-II, LED-III, and LED-IV are 20.92%, 24.65%, 27.28%, and 33.77% and the wall-plug efficiencies are 17.11%, 20%, 22.5%, and 27.33%, respectively. The enhanced performance is attributed to the light output power enhancement through the surface roughness, microlens-liked PS hemisphere, and scatter-liked HHPS array. In this paper, the rigorous coupled wave analysis (RCWA) numerical method was also conducted to demonstrate the HHPS array effectively enlarge the effective light cone.
Method of compensating for pixel migration in volume holographic optical disc (VHOD)
(2012-09-10)
Yu, Yeh-Wei
;
Cheng, Chih-Yuan
;
Teng, Tun-Chien
;
Chen, Cheng-Hsien
;
Lin, Shiuan-Huei
Volume holographic optical disc (VHOD) technology is simpler than the angular multiplexing holographic system. However, disc rotation usually causes pixel migration, thus reducing signal quality. This study proposes a special geometrical arrangement to counteract pixel migration. Using paraxial approximation analysis, an optimal geometrical distance ratio, K, is calculated to compensate for pixel migration and improve image quality during disc rotation. The results of approximation analysis are confirmed by both simulation and experimental results. (C) 2012 Optical Society of America