Single-Mode Lasing from Coupled Whispering Gallery ZnO Microrods
Zen-Jia Jiang1, Wei-Chen Liao1, Yu-Yu Chen1, Chiang-Lun Wang3, Kai-Hsiang Lin1, Chung-Lin Wu3, Shih-Hui Chang1, Hsu-Cheng Hsu1,2*
1Department of Photonics, National Cheng Kung University, Tainan, Taiwan
2Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, Taiwan
3Department of Physics, National Cheng Kung University, Tainan, Taiwan
* presenting author:Hsu-Cheng Hsu,
We demonstrate single-mode ultraviolet lasing from coupled ZnO microrods through optical pumping. Two ZnO microrods with slightly different diameters were placed side-by-side and corner-to-corner in contact to form a coupled cavity. The single mode selection mechanism is realized by the Vernier effect of coupled cavities in the microrods, which strongly expand the free space range. A superior single-mode performance includes side-mode-suppression ratio, high quality factor and low lasing threshold was achieved in the side-by-side coupled cavity system. Numerical simulations reveal that only one mode could survive in the coupled ZnO microrods. The results indicate an accessible route to realizing single-frequency for sensing, optical data storage, and bio-related applications.

Keywords: ZnO microrod, Vernier effect, single-mode lasing