Near-infrared subwavelength imaging using Al:ZnO-based near-field superlens

Near-field subwavelength imaging has been realized at visible and mid-infrared frequencies, but it has not been achieved at near-infrared (NIR). In this work, the transparent conducting oxides (TCO)-based near-field superlenses working at NIR frequencies were proposed. As one of easily available TCO materials, Al-doped ZnO (AZO) was considered in both stratified ZnO-AZO-ZnO and single-layered AZO structures, which had the subwavelength resolution of better than λ/25 at a wavelength of 2.57μm andλ/20 at 2.01μm, respectively. These findings reveal that the TCO can find the applications not only in liquid-crystal displays, photovoltaic devices, and electromagnetic interface shielding, but also in superresolution and subsurface imaging at NIR frequencies.