1. Department of Electrical Engineering, National Chung Hsing University, Taichung, Taiwan
2. Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan
3. Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung, Taiwan
4. Department of Electronic Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung, Taiwan