In-depth study on resonant tunneling for subwavelength imaging

Abstract

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.

A novel approach to Fabry–Pérot-resonance-based lens and demonstrating deep-subwavelength imaging

“…Furthermore, due to the dependence on thickness, the lens becomes bulky for low-frequency imaging. To overcome this, another type of anisotropic acoustic metamaterial has been reported based on the resonant tunneling method [38][39][40] . The frequency was made independent of the thickness using the Bloch wave resonance, which can be achieved by diameter modulation.…”

Metamaterial Lensing Devices

“…As shown in Figure 1a, since the metamaterial (artificial medium) has a negative refractive index and an evanescent wave amplification characteristic, the evanescent wave (Fourier component) emitted by the electromagnetic wave source will not only be corrected in phase but also its amplitude will be effectively amplified. This can lead to perfect recovery of the object’s information at the image point [95,96,97], breaking the diffraction limited resolution of traditional lens, and achieving the purpose of super-resolution (sub-wavelength) focusing of electromagnetic waves. Figure 1b shows an example of a silver slab lens in operation.…”