Browsing by Author "Wu, Tzeng Tsong"

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Sub-wavelength GaN-based membrane high contrast grating reflectors
(2012-08-27)
Wu, Tzeng Tsong
;
Syu, Yu Cheng
;
Wu, Shu Hsien
;
Chen, Wei Ting
;
Lu, Tien Chang
The GaN-based membrane high contrast grating (HCG) reflectors have been fabricated and investigated. The structural parameters including grating periods, grating height, filling factors and air-gap height were calculated to realize high reflectivity spectra with broad bandwidth by the rigorous coupled-wave analysis and finite-difference time-domain method. Based on the optimized simulation results, the GaN-based membrane HCGs were fabricated by e-beam lithography and focused-ion beam process. The fabricated GaN-based membrane HCG reflectors revealed high reflectivity at 460 nm band with large stopband width of 60 nm in the TE polarization measured by using the micro-reflectivity spectrometer. The experimental results also showed a good agreement with simulated ones. We believe this study will be helpful for development of the GaN-based novel light emitting devices in the blue or UV region. (C) 2012 Optical Society of America
Suspended GaN-based band-edge type photonic crystal nanobeam cavities
(2014-02-10)
Wu, Tzeng Tsong
;
Chen, Hao Wen
;
Lan, Yu Pin
;
Lu, Tien Chang
;
Wang, Shing Chung
We demonstrated GaN-based photonic crystal (PC) nanobeam cavities by using the e-beam lithography and the suspended nanobeams were realized by focused-ion beam (FIB) milling. One resonant mode was clearly observed at 411.7 nm at 77K by optical pumping. The quality factor was measured to be to 7.4 x 10(2). Moreover, the degree of polarization value was measured to be 40%. The temperature-dependent characteristics were measured and discussed, which unambiguously demonstrated that the observed resonant peak originated from the band-edge mode of the one-dimensional PC nanobeam. (C) 2014 Optical Society of America