In-depth study on resonant tunneling for subwavelength imaging

We report new frequency bands for subwavelength imaging by using the resonant tunneling method which have not been explored previously. As per the existing theory of resonant tunneling, imaging frequency is limited for a certain number of crystals. However, after conducting an analytical analysis over a wide range of frequencies, we observed that higher frequencies do exist for subwavelength imaging. We verified this observation both numerically and experimentally. We extended our study to observe the effect of lattice periodicity on image resolution. By reducing periodicity during experiment, we achieved a resolution of λ/9.5 at the conventional region and λ/2.45 at the higher band region.