Designing Broadband Nanoimaging with Anomalous Hyperbolic Dispersion

TLDR: In this paper, a folded-geometry transformation was proposed for broadband nano-imaging of microworld in the near field using hyperbolic metamaterials with engineered anomalous Hyperbolic dispersion.

Abstract: A novel strategy to broadband nanoimaging of microworld in the near field is reported by using a folded-geometry transformation. This approach relies exclusively on hyperbolic metamaterials with engineered anomalous hyperbolic dispersion. The restriction on the signs of gradient in the dispersion enables invariable propagation angle of hyperbolic polaritons at different wavelengths, which could be utilized to dramatically broaden the bandwidth. Interestingly, a pseudo-broadband nanoimaging based on hyperbolic metamaterial consisting of alternating metal (e.g. Ag) and plasmonic nanocomposite (e.g. Au-Al2O3) layers is demonstrated. Such strategy of transformation optics-based broadband nanoimaging allows for a new class of robustly manufacturable nanophotonic systems, although additional gain-assisted compensation is needed to improve the performance of nanoimaging.