Tunable flat lens with liquid metal metamaterial

In this paper, we demonstrate tunable flat lens with liquid metal. The flat lens consists of 9 × 9 split ring resonators (SRR), which can be controlled individually by a ternary-notation control system. Each SRR metamaterial unit cell is formed by liquid metal (mercury) with approximately 1.5 μL, which offer high flexibility in geometry reconfiguration. In experiment, it demonstrates freely tuning of the sub-wavelength focus point at 20-cm focus length, which is approximately 10 times of the incident wavelength.