Yisha You's research while affiliated with University of Electronic Science and Technology of China and other places

Inspired by imaging principle of near-field scanning optical microscope (NSOM), meta-pillars array is designed and analyzed on the basis of microscopic imaging application with high resolution. Finely focused spots acting as tiny secondary sources for illumination at near-field can be derived under supporting of the meta-pillars for the purpose of increasing imaging resolution. Numerical calculation is carried out on the basis of finite difference and time domain (FDTD) algorithm. Our calculation results demonstrate that the meta-pillars are capable of supporting the microscopic imaging at sub-wavelength resolution.

A novel metasurface-based nanoantennas array fabricated using a technique of heavy ion tracking is introduced. The technique has advantages of large area patterning, high aspect ratio of the nanoantennas, controllable length, and multi-choice of materials etc. Fabrication process, numerical calculation and optical near-field characterization of the structure are presented. Evidenced by probing results of our near-field scanning optical microscope, the sharp nanoantennas with high aspect ratio can scattering as tiny hot-spots with beam sopt size as small as 50 nm in near-field region. Sensitivity of 137 nm/RIU is obtained for sensing ethanol on the basis of spectroscopy results. Our theoretical and experimental results demonstrate that this structure not only is capbale of acting as a biochemistry sensors for immunoassay and cell/molecular spectrocopy, but also has potential applications in bioimaging due to the nanofocusing hot-spots formed by the sharp nano-pillars array with high-aspect ratio.

A simplified and cost-effective optical absorber is designed by means of optimization on the basis of finite domain and time difference (FDTD) algorithm. It is suitable for fabrication and mass production in future industry. To investigate its absorbing performance and photo-thermal effect, experiments are carried out using focused ion beam nanofabrication, characterization of spectroscopy, and measurement of temperature rise. Our experimental results demonstrate that the absorber is possible to be used in photo-thermal therapy for tumor/cancer cells.