Browsing by Author "Wang, Hsiao-Tsung"

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Dynamic Tuning and Memory Switching of Defect Modes in a Hybrid Photonic Structure
(2016-10-01)
Wang, Hsiao-Tsung
;
Wu, Po-Chang
;
Timofeev, Ivan V.
;
Zyryanov, Victor Ya.
;
Lee, Wei
We propose a memorable and electrically tunable photonic device by infiltrating a dual-mode chiral-doped dual-frequency liquid crystal (LC) as the central defect layer in a one-dimensional photonic crystal (PC). According to the transmission properties of this structure, the wavelength tunability of defect modes is obtained by manipulating the LC layer in the dynamic mode due to the electrically controlled birefringence effect. Moreover, the switching between two memorable states, the splay and pi-twist states, creates two distinct sets of defect modes at null voltage. The spectral characteristics of this device ensure its potential application as an energy-efficient multichannel wavelength filter.
Thermodielectric generation of defect modes in a photonic liquid crystal
(2014-02-10)
Hsiao, Yu-Cheng
;
Wang, Hsiao-Tsung
;
Lee, Wei
;
光電學院
;
College of Photonics
Photonic defect modes induced by in situ formation of an ill-defined defect layer is demonstrated in a cholesteric liquid crystal (CLC). The local deformation of the one-dimensionally periodic helical structure is achieved by means of the thermodielectric effect, which alters the pitch in the middle of the cholesteric structure. The defect-mode peak in the photonic band gap appears in the transmission spectrum only when the incident circularly polarized light has the same handedness as that of the CLC structure. The wavelength of the deformation-induced defect mode can be tuned upon varying the dielectric heating power by simply applying a frequency-modulated voltage. (C) 2014 Optical Society of America
Tunable narrow-bandpass filter based on an asymmetric photonic bandgap structure with a dual-mode liquid crystal
(2014-06-16)
Wang, Hsiao-Tsung
;
Timofeev, Ivan V.
;
Chang, Kai
;
Zyryanov, Victor Ya.
;
Lee, Wei
A one-dimensional asymmetric photonic crystal with dual-frequency liquid crystal as a central defect layer was demonstrated. Such asymmetric structure was characterized by the dramatic increase in intensity of the electric field of light localized at the overlapped photonic bandgap edges, thereby enhancing the observed transmittance of the spectral windows originating from the defect layer. The defect layer was made of a dual-mode liquid crystal that exhibited not only electrical tunability and switchability but also optical bistability. Consequently, tunable and bistable defect modes can be realized in the photonic structure. This asymmetric photonic crystal structure is promising and should be further explored for photonic device applications. (C) 2014 Optical Society of America
Ultralow-threshold single-mode lasing based on a one-dimensional asymmetric photonic bandgap structure with liquid crystal as a defect layer
(2014-06-15)
Wang, Hsiao-Tsung
;
Lin, Jia-De
;
Lee, Chia-Rong
;
Lee, Wei
;
光電學院
In this Letter, we propose defect-mode lasing from a one-dimensional asymmetric photonic structure with dye-doped nematic liquid crystal as a central defect layer. The local field intensity of the distinguished single defect mode at the overlapped photonic band edges is drastically enhanced by the asymmetric structure consisting of two distinct multilayer photonic crystals. With high density of states of photons, effective output lasing emission and maximum input excitation are ensured. As a result, the single-mode lasing with a low excitation threshold of 0.2 mu J/pulse is achieved due to the combination of the defect layer and the photonic band edge effect. (C) 2014 Optical Society of America