Photorealistic rendering of unidirectional free-space invisibility cloaks

TL;DR

This paper uses photorealistic ray tracing to visualize and compare the performance of four types of unidirectional free-space invisibility cloaks in three dimensions, highlighting their strengths and limitations.

Contribution

It provides a detailed visualization of unidirectional cloaks' performance in 3D for various viewing angles and polarizations, aiding understanding of their practical capabilities.

Findings

Unidirectional cloaks work perfectly only for specific directions and polarizations.

Visualization reveals the virtues and limitations of different cloak designs.

Performance varies significantly with viewing angle and polarization.

Abstract

Carpet or ground-plane invisibility cloaks hide an object in reflection and inhibit transmission by construction. This concept has significantly reduced the otherwise demanding material requirements and has hence enabled various experimental demonstrations. In contrast, free-space invisibility cloaks should work in both reflection and transmission. The fabrication of omnidirectional three-dimensional free-space cloaks still poses significant challenges. Recently, the idea of the carpet cloak has been carried over to experiments on unidirectional free-space invisibility cloaks that only work perfectly for one particular viewing direction and, depending on the design, also for one linear polarization of light only. Here, by using photorealistic ray tracing, we visualize the performance of four types of such unidirectional cloaks in three dimensions for different viewing directions and different polarizations of light, revealing virtues and limitations of these approaches in an intuitive manner.