1. Institute of Innovative Research (IIR), Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
2. Key Laboratory of Photonic Information Technology, Ministry of Industry and Information Technology, Beijing Institute of Technology, No.5 Yard, Zhong Guan Cun South Street, Haidian District, Beijing 100081, China
3. Ambition Photonics Inc., Tokyo Tech Yokohama Venture Plaza E208, Yokohama 226-8510, Japan
4. Photonic Network Laboratory, National Institute of Information and Communications Technology, 4-2-1, Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan