Optimized mid-infrared thermal emitters for applications in aircraft countermeasures

Abstract

We introduce an optimized aperiodic multilayer structure capable of broad angle and high temperature thermal emission over the 3 μm to 5 μm atmospheric transmission band. This aperiodic multilayer structure composed of alternating layers of silicon carbide and graphite on top of a tungsten substrate exhibits near maximal emittance in a 2 μm wavelength range centered in the mid-wavelength infrared band traditionally utilized for atmospheric transmission. We optimize the layer thicknesses using a hybrid optimization algorithm coupled to a transfer matrix code to maximize the power emitted in this mid-infrared range normal to the structure’s surface. We investigate possible applications for these structures in mimicking 800–1000 K aircraft engine thermal emission signatures and in improving countermeasure effectiveness against hyperspectral imagers. We find these structures capable of matching the Planck blackbody curve in the selected infrared range with relatively sharp cutoffs on either side, leading to increased overall efficiency of the structures. Appropriately optimized multilayer structures with this design could lead to matching a variety of mid-infrared thermal emissions. For aircraft countermeasure applications, this method could yield a flare design capable of mimicking engine spectra and breaking the lock of hyperspectral imaging systems.

Catenary Electromagnetics for Ultra‐Broadband Lightweight Absorbers and Large‐Scale Flat Antennas

“…The well‐known example is the case of 1D photonic crystals (they can be treated as unpatterned metasurfaces) that their optical responses can be quantitatively calculated by the transfer matrix method . As a result, many optimization methods for these structures are proposed and the robustness of this kind of structures shows great advances over their patterned counterparts . Although previous works demonstrated that some patterned metasurfaces can be well described by a mathematical model, the conclusion is drawn by retrieval methods that cannot be employed for inverse designs directly …”

Advanced mid-infrared lightsources above and beyond lasers and their analytical utility

“…Additional applications of the presented MIR emitters/absorbers worth mentioning here are beyond analytical scenarios and go beyond the scope of the present review, e.g., among others in military for stealth technology and thermovoltaics [ 3 , 104 , 105 ], and for power generation scenarios [ 44 , 56 , 106 , 107 ].…”

“…When illuminating samples with MIR radiation, fundamental rotational and vibrational resonances within virtually any kind of molecule—with few exceptions—independent of molecular weight, complexity, dimension, physical status (i.e., gas, liquid, semi-solid, solid) or nature (i.e., organic and inorganic) are excited. Hence, the MIR spectrum of a sample is frequently referred to as the ‘molecular fingerprint’ enabling the detection and quantification of a wide range of relevant molecular compounds in environmental, health and medical, industrial, and security and defense applications [ 1 – 3 ].…”

Optimized Multilayer Structures With Ultrabroadband Near-Perfect Absorption

“…Broadband near-perfect absorbers, operating in the visible and near-infrared wavelength ranges, have been widely investigated-due to their many potential applications in chemical sensing [1]- [3], thermophotovoltaic energy conversion [4], [5], imaging [6], color filters [7], [8], and thermal emitters [9]- [13]. Broadband near-perfect absorption requires almost perfect impedance matching between the structure and air over a broad wavelength range [14]- [16].…”