Broadband polygonal invisibility cloak for visible light

Area of Science:

• Optics and Photonics
• Materials Science
• Electromagnetism

Background:

• Invisibility cloaks are a significant area of research, driven by transformation optics and conformal mapping theories.
• Implementing cloaks requires extreme material properties and spatially dependent parameters, posing significant fabrication challenges.
• Achieving isolated invisibility cloaks in the visible light spectrum remains an elusive goal.

Purpose of the Study:

• To design and experimentally demonstrate an isolated polygonal invisibility cloak for visible light.
• To overcome the implementation challenges associated with extreme material properties in cloaking devices.
• To provide a foundational step towards the realization of fully movable invisibility cloaks.

Main Methods:

• The cloak design utilizes a linear homogeneous transformation method to define electromagnetic parameters for its constituent elements.
• Theoretical analysis was performed to confirm the cloak's ability to render objects invisible from all incident directions.
• A simplified hexagonal cloak was fabricated using natural anisotropic materials for experimental validation.

Main Results:

• An isolated polygonal cloak for visible light was successfully designed and experimentally demonstrated.
• The fabricated hexagonal cloak exhibited cloaking properties for six specific incident directions.
• Experimental validation confirmed the cloak's performance across a broadband visible spectrum.

Conclusions:

• The study presents a practical design and experimental proof-of-concept for an isolated invisibility cloak in the visible spectrum.
• The employed linear homogeneous transformation method offers a viable approach for designing cloaking devices with achievable material parameters.
• This work represents a significant advancement in the pursuit of practical invisibility cloaking technologies.