Structure design and theoretical study on infrared optical properties of Ag/Ge core shell particles

To obtain particles that meet the requirements of spectral selective radiation for infrared stealth， the infrared optical properties of Ag/Ge core-shell structures were calculated using Mie scattering theory and finite element simulation， respectively. The peak extinction efficiency of particles with different Ag core and Ge shell size combinations was studied. The extinction efficiency curves of different size combinatorial calculators were selected on the contours of 6.5 μm， and the 0.3/0.848 μm core-shell structure was determined by comparison.The extinction efficiency was calculated by Mie scattering theory and finite element simulation. The curves of the two methods are very similar. The extinction peaks are all at 6.5 μm， and the peak extinction efficiency is 16.6 and 16.1， respectively， which verifies the reliability of the calculated results.By comparing the three-dimensional far-field radiation and electromagnetic power loss of particles in different wavelength， the particles have stronger radiation intensity and power loss density at 6.5 μm. The results indicate that the particle have a strong resonance with the incident field， which can be used for the selective absorption of infrared radiation in this band.