Super-resolution imaging using a three-dimensional metamaterials nanolens has been recently reported [B. D. F.
Casse et al. Appl. Phys. Lett. 96, 023114 (2010)]. This nanolens, consisting of bulk gold nanowires embedded
in alumina template, can transport with low-loss object details down to λ/4 (λ, wavelength) length scales, over
significant distances of the order of 6λ. Here, we present validation of the super-resolution imaging by the nanolens
through extensive control experiments. We also analytically show that the nanowire array medium supports a
quasi transverse electromagnetic mode (TEM) with flat isofrequency contours, which is a requirement for super-resolution
imaging. We numerically compute the optical transfer function to quantify the imaging quality of
the lens and show that the theoretical resolution of this nanolens is λ/5. Additionally, we demonstrate the
broadband nature of the lens in the spectral region 1510 nm to 1580 nm. Finally, imaging of a large object
(~ 52λ in diameter), with subwavelength features, is presented.
Up to date, electromagnetic metamaterials (EM<sub>3</sub>) have been mostly fabricated by primary pattern generation via electron beam or laser writer. Such an approach is time-consuming and may have limitations of the area filled with structures.
Especially, electron beam written structures are typically confined to areas of a few 100×100 μm<sup>2</sup>. However, for meaningful technological applications, larger quantities of good quality materials are needed. Lithography, in particular X-ray deep lithography, is well suited to accomplish this task. Singapore Synchrotron Light Source (SSLS) has been applying its LIGA process that includes primary pattern generation via electron beam or laser writer, X-ray deep
lithography and electroplating to the micro/nano-manufacturing of high-aspect ratio structures to produce a variety of EM<sup>3</sup> structures. Starting with Pendry's split ring resonators, we have pursued structure designs suitable for planar lithography since 2002 covering a range of resonance frequencies from 1 to 216 THz. More recently, string-like structures have also been included. Latest progress made in the manufacturing and characterization of quasi 3D
metamaterials having either split ring or string structures over areas of about ≈1 cm<sup>2</sup> extension will be described.