Subwavelength imaging of periodic and isolated nanostructures through silver superlens

The superlens nanolithography is a promising technique for patterning nanoscale structures because of its ability to overcome the diffraction limit. Until 2005, Zhang and his co-works successfully obtained images such as line grating and NANOalphabet through a thin silver film with a UV light at 365 nm wavelength and the resolution is down to 1/6 of the incidence wavelength. In this paper, subwavelength imaging of periodic and isolated nanostructures through a new silver superlens is investigated by appropriately choosing the material and designing the thickness of each layer in the lens structure as well as controlling the experimental procedure. The superlens structure was optimized by means of the transfer transmission matrix method. Subwavelenght imaging of periodic and isolated nanostructures was performed through this superlens structure. The experiments show that for periodic nanostructures the imaging resolution is about 100 nm, while for isolated nanostructues the resolution is below 50 nm, less than 1/7 of the incidence wavelength.