Robust large dimension terahertz cloaking

TL;DR

This paper presents the first homogeneous terahertz invisibility cloak using sapphire crystals, achieving large concealed volumes, broad bandwidth, and low loss, overcoming limitations of previous metamaterial-based cloaks.

Contribution

It introduces a novel, simple, and scalable approach to terahertz cloaking with a homogeneous sapphire-based device, enabling larger objects to be hidden without complex fabrication.

Findings

Demonstrated a homogenous terahertz invisibility cloak using sapphire.

Achieved broad bandwidth and low loss in cloaking performance.

Enabled hiding of objects nearly ten times larger than previous methods.

Abstract

Invisibility cloaking not only catches the human imagination, but also promises fascinating applications in optics and photonics. By manipulating electromagnetic waves with metamaterials, researchers have been able to realize electromagnetic cloaking in the microwave, terahertz and optical regimes. Nevertheless, the complex design and fabrication process, narrow bandwidth, and high intrinsic losses in the metamaterial-based cloaks have imposed intractable limitations on their realistic applications. Seeking new approaches to overcome these perceived disadvantages is in progress. Here by using uniform sapphire crystal, we demonstrate the first homogenous invisibility cloak functioning at terahertz frequencies. The terahertz invisibility device features a large concealed volume, low loss, and broad bandwidth. In particular, it is capable of hiding objects with a dimension nearly an order of magnitude larger than that of its lithographic counterpart, but without involving complex and time-consuming cleanroom processing. Such homogenous invisibility cloaks may lead to novel terahertz photonic devices potentially used in medicine, radars, and communications.