1. Department of Physics National Dong Hwa University Hualien 974301 Taiwan
2. Department of Optoelectronics and Materials Technology National Taiwan Ocean University Keelung 20224 Taiwan
3. Department of Electrical and Computer Engineering University of California Los Angeles CA 90095 USA
4. Department of Electric Engineering and Graduate Institute of Optoelectronic Engineering National Chung Hsing University Taichung 40227 Taiwan
5. Department of Opto‐Electronic Engineering National Dong Hwa University Hualien 974301 Taiwan
6. Department of Dermatology National Taiwan University Hospital and College of Medicine National Taiwan University Taipei 100229 Taiwan