Controllable near-field intensity and spot size of hybrid terahertz metamaterial

We report controllable near fields around split-ring resonator (SRR) gaps of an active terahertz metamaterial. As extension of parallel-plate capacitors, patterned VO2 is integrated into the metallic SRRs to manipulate the near-field intensity and hot spot size through its metal-insulator transition. This design enhances the device reliability by preventing VO2 dielectric breakdown at a strongly enhanced near field. The near-field intensity and spot size are tunable in broad ranges, and the device is demonstrated to be capable of compensating resonant frequency drift arisen from different interactions due to near-field coupling. It provides an effective method to actively manipulate the light-matter interaction through the strongly enhanced and tunable near fields. (C) 2015 Optical Society of America