A Carpet Cloak Device for Visible Light

TL;DR

This paper presents a visible light invisibility cloak made with silicon nitride that uses quasi conformal mapping and nano-porous substrates to achieve broadband, low-loss invisibility across the visible spectrum.

Contribution

The work introduces a novel fabrication method for a visible light cloak using nano-porous silicon oxide and silicon nitride, enabling broadband invisibility with low loss.

Findings

Demonstrates wideband invisibility in the visible spectrum

Uses nano-porous silicon oxide for low refractive index

Achieves low-loss, broadband cloaking

Abstract

We report an invisibility carpet cloak device, which is capable of making an object undetectable by visible light. The cloak is designed using quasi conformal mapping and is fabricated in a silicon nitride waveguide on a specially developed nano-porous silicon oxide substrate with a very low refractive index. The spatial index variation is realized by etching holes of various sizes in the nitride layer at deep subwavelength scale creating a local effective medium index. The fabricated device demonstrates wideband invisibility throughout the visible spectrum with low loss. This silicon nitride on low index substrate can also be a general scheme for implementation of transformation optical devices at visible frequency.