Reconfigurable Near-Field Focusing Reflector Based on Superoscillation Mechanism

Superoscillation is an extraordinary phenomenon capable of generating small-size focusing spots, which can be used for super-resolution focusing and imaging. Herein, we elaborate on a reconfigurable near-field focusing reflector based on the superoscillation principle, where the focal position and operation frequencies are modulated by the dynamic phase-compensation mechanism of an engineered metamirror. A varactor diode is embedded into each resonant meta-atom, enabling to achieve nearly 340° phase coverage. To validate the proposed reflector, the fabricated metamirror platform is experimentally measured in an anechoic chamber. The results show that the near-field focusing maintains subdiffraction property when the focal distances and frequencies are flexibly driven by the metamirror. Such a focusing reflector holds great integration potential to imaging devices for its tunability, high resolution, and nonnarrowband features.