Near‐Field Photodetection in Direction Tunable Surface Plasmon Polaritons Waveguides Embedded with Graphene oleh Chia‐Hung Wu, Chih‐Jen Ku, Min‐Wen Yu, Jhen‐Hong Yang, Pei‐Yuan Wu, Chen‐Bin Huang, Tien‐Chang Lu, Jer‐Shing Huang, Satoshi Ishii, Kuo‐Ping Chen