Broadband and Ultrathin Infrared Stealth Sheets

Abstract

To effectively hide objects and render them invisible to thermographic detectors, their thermal signatures in the infrared (IR) region of the spectrum may be concealed. However, to conceal broadband spontaneous thermal emission of objects, covering the mid- and long-IR is a major obstacle. Here, metallic-dielectric nanostructures and microscale IR emitters are integrated and transferred onto thin flexible substrates to realize IR stealth sheets. The nanostructures absorb and scatter a broad band of IR wavelengths to reduce both reflection and transmission to below 5% across a wide range from 2.5 to 15.5 μm, and thus significantly attenuate the amount of IR signals propagating toward the detectors. Results show that the nanostructures with their unique properties can almost completely conceal the thermal emission from objects and blend them into their surroundings. In addition, micro-emitters thermally isolated from the broadband absorbers can present false thermography to deceive IR detectors and heat-sensing cameras.