Browsing by Author "Wang, Yow-Gwo"

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Lasing in metal-coated GaN nanostripe at room temperature
(2011-03-28)
Wang, Yow-Gwo
;
Chen, Cheng-Chang
;
Chiu, Ching-Hsueh
;
Kuo, Ming-Yen
;
Shih, M. H.
This study demonstrated a metal-coated GaN nanostripe laser operable at room temperature. The ultraviolet lasing mode was observed at a wavelength of approximately 370 nm with a low threshold power density of 0.042 kW/cm(2). The lasing mode of the metal-coated nanostripe was characterized using finite-element method simulation. The results showed the significance of metal coatings in this nanocavity structure for lasing at room temperature. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3572023]
Magnetically tunable metallic photonic crystals immersed in liquid crystal for terahertz wave
(2012)
Pan, Ru-Pin
;
Shih, Chih-Chang
;
Tang, Tsung-Ta
;
Wang, Yow-Gwo
;
Wu, Hsin-Ying
We investigated the phenomena of a metallic photonic crystal (MPC) immersed in liquid crystal. According to our design, the photonic crystal has specific photonic band gap (PBG) and can be utilized as a filter. The device is filled with nematic liquid crystal (NLC), MDA-00-3461. The refractive indices of NLC can be magnetically controlled by reorienting the NLC molecules. Consequently, the corresponding PBG and the filtering performance of the device are tunable. According to our experimental results, the low frequency boundary of PBG at 0.121 THz can be blue shifted by 6.17 GHz, and the high frequency boundary of PBG at 0.175 THz can be shifted to the blue by 11.04 GHz. As a tunable THz filter, the peak transmittance at 0.187 THz can be blue shifted by 3.66 GHz.
Room temperature lasing with high group index in metal-coated GaN nanoring
(2011-12-19)
Wang, Yow-Gwo
;
Chang, Shu-Wei
;
Chen, Cheng-Chang
;
Chiu, Ching-Hsueh
;
Kuo, Ming-Yen
The room temperature lasing action from a metal-coated GaN nanoring cavity was observed by optical pumping. The GaN nanoring is 7 mu m in diameter and 400 nm in width. The quality factor of the cavity is approximately 860 with a threshold power density of 37.5 mJ/cm(2). Such a device performance was attributed to the combination of metal-coated nanocavity with whispering-gallery modes. Moreover, the group index extracted from the experiment was 5.99 and was verified with calculations and analyses of the lasing modes as well as their characteristics. The study showed a promising way to further improve the performance of metal-coated nanolasers. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3671648]