Macroscopic Invisibility Cloak for Visible Light

TL;DR

This paper demonstrates a practical, low-cost macroscopic invisibility cloak for visible light using calcite, capable of concealing objects larger than 3500 wavelengths across a broad color spectrum.

Contribution

It introduces a novel, simple fabrication method for a visible-light cloak that works on macroscopic objects and broad bandwidths, advancing practical invisibility technology.

Findings

Successfully cloaked objects up to 2 mm in height

Achieved broadband operation across red, green, and blue light

Used low-cost materials and simple manufacturing techniques

Abstract

Invisibility cloaks, a subject that usually occurs in science fiction and myths, have attracted wide interest recently because of their possible realization. The biggest challenge to true invisibility is known to be the cloaking of a macroscopic object in the broad range of wavelengths visible to the human eye. Here we experimentally solve this problem by incorporating the principle of transformation optics into a conventional optical lens fabrication with low-cost materials and simple manufacturing techniques. A transparent cloak made of two pieces of calcite is created. This cloak is able to conceal a macroscopic object with a maximum height of 2 mm, larger than 3500 free-space-wavelength, inside a transparent liquid environment. Its working bandwidth encompassing red, green and blue light is also demonstrated.