Hiding a realistic object using a broadband terahertz invisibility cloak

Area of Science:

• Metamaterials and Nanophotonics
• Electromagnetism and Optics
• Terahertz Science and Technology

Background:

• Invisibility cloaking, utilizing transformation optics, aims to render objects undetectable by manipulating electromagnetic fields.
• Previous cloaking demonstrations were limited to microwave and optical frequencies.
• The Terahertz (THz) domain, crucial for spectroscopy, lacked practical 3D cloaking solutions due to fabrication challenges.

Purpose of the Study:

• To experimentally demonstrate the first 3D Terahertz (THz) invisibility cloak.
• To overcome fabrication limitations for creating optically large cloaking devices in the THz range.
• To validate the cloaking device's effectiveness in concealing both geometrical and spectroscopic properties.

Main Methods:

• Fabrication of a 3D THz cloaking device using a scalable Projection Microstereolithography process.
• Characterization of the cloak's performance over a broad frequency range (0.3–0.6 THz).
• Utilizing angular-resolved reflection THz time-domain spectroscopy (THz-TDS) for detailed analysis.

Main Results:

• Successful experimental demonstration of a 3D THz cloaking device.
• The cloak operated effectively across a wide THz frequency band (0.3–0.6 THz).
• The device successfully rendered a rectangular α-lactose monohydrate absorber undetectable, hiding its geometrical and spectroscopic signatures.

Conclusions:

• The developed 3D THz cloaking device represents a significant advancement in invisibility technology.
• Projection Microstereolithography offers a scalable method for fabricating complex THz cloaking structures.
• This work opens new possibilities for THz cloaking applications in various scientific and technological fields.