1. Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei 106, Taiwan
2. Taiwan Semiconductor Manufacturing Company (TSMC), Hsinchu 300, Taiwan
3. Department of Electro-Optical Engineering, National Taipei University of Technology, Taipei 106, Taiwan
4. TSMC-NTU Joint Research Center, National Taiwan University, Taipei 106, Taiwan