1. Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 300044, Taiwan.
2. Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300044, Taiwan.
3. Department of Physics, National Tsing Hua University, Hsinchu 300044, Taiwan.
4. Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu, Taiwan.