Achieving sub-wavelength imaging through a flat hyperlens in a modified anodic aluminum oxide template

Constrained by the diffraction limit, a lens can only resolve features larger than half of the incident wavelength owing to the decaying nature of evanescent waves. Several novel devices have been proposed, for example, superlenses and hyperlenses to break this limit. In this work, we present a flat hyperlens composed of silver nanowires embedded in a modified anodic aluminum oxide (AAO) template to demonstrate subwavelength imaging. Measurement conducted by the near-field scanning optical microscope at 633 nm suggests that our proposed flat hyperlens can indeed achieve sub-wavelength imaging with a resolution down to 0.34λ and 0.25λ along two orthogonal directions. Furthermore, to confirm the resolution limit of the flat hyperlens, numerical simulations were performed at the incident wavelengths of 633 and 365 nm, and the corresponding resolution were 0.19λ and 0.3λ, respectively, thus paving a route for sub-wavelength photolithography.