Multiple Resonance Metamaterial Emitter for Deception of Infrared Emission with Enhanced Energy Dissipation

Abstract

Artificial camouflage surfaces for assimilating with the environment have been utilized for controlling optical properties. Especially, the optical properties of infrared (IR) camouflage materials should be satisfied with two requirements: deception of IR signature in a detected band through reduced emissive energy and dissipation of reduced emissive energy for preventing thermal instability through an undetected band. Most reported articles suggest the reduction of emissive energy in the detected band; however, broadband emission for enough energy dissipation through the undetected band simultaneously is still a challenging issue. Here, we demonstrate the multiresonance emitter for broadband emission with IR camouflage utilizing the electromagnetic properties of dielectric material. We reveal that the interaction between the magnetic resonance and dielectric layer’s property in a metal–dielectric–metal structure induces the multiple resonance at the specific band. We present an IR camouflage behavior of multiresonance emitter on a curved surface through the IR camera (8–14 μm). We evaluate the energy dissipation in the undetected band, which is 1613% higher than metal and 26% higher than conventional selective emitters. This study paves the way to develop broadband emitters for radiative cooling and thermophotovoltaic applications.

Flexible Assembled Metamaterials for Infrared and Microwave Camouflage

“…It is difficult to use IR camouflage materials in case of flexible polymers because the dielectric layer has lots of lattice resonance in IR band which induces unwanted resonances. [ 37,45 ] Hence, the structure of IR camouflage materials should be changed, such as disconnecting the brittle part to reduce the mechanical stress. [ 42 ] As a dielectric layer, silicon nitride (Si 3 N 4 ) was adopted for FAM.…”

“…Ti was used as an adhesive layer which did not affect the FIRE performance. [19,28,33,37] The silicon nitride for a dielectric layer and Au/Ti layers for metal patterns were deposited by plasma enhanced chemical vapor deposition (PECVD, Plasma Therm 790 Series, Plasma Therm USA) and E-beam evaporator after lifting off the photoresist, respectively. Photoresist patterns were fabricated on metal (Au)-dielectric (Si 3 N 4 )-metal (Au) layers for disk structure by controlling the magnitude of exposure dose (50-200 mJ cm −2 ) by varying the diameter of the unit cell.…”

“…[ 33 ] Therefore, there have been several studies on metamaterials for camouflage with a specific property of the unity absorptivity for microwave [ 30,31,34 ] or reflectivity for IR wave. [ 33,35–37 ]…”

“…However, it is inappropriate as a dielectric layer in IR camouflage materials because it induces the multi‐resonance, making their manipulation in the IR regime difficult. [ 37 ] It implies that the flexible IR camouflage material with the dielectric layer not to induce multi‐resonances should be assembled to the flexible microwave absorber (FMWA) separately. Disconnecting the brittle layer as the engineering solution to reduce the mechanical stress leads to the flexible structure for arbitrary surfaces [ 42 ] similar to the conventional IR camouflage materials.…”

“…[33] Therefore, there have been several studies on metamaterials for camouflage with a specific property of the unity absorptivity for microwave [30,31,34] or reflectivity for IR wave. [33,[35][36][37] However, only a few studies of the multispectral metamaterials have been conducted [38,39] since they should solve the issue of size difference depending on the target wavelength. In metamaterials, the operating wavelength is proportional to the unit cell size.…”