Forbidden Band Broadening of Photonic Crystal for Wide Waveband Infrared Stealth

摘要

In order to achieve 1～14μm infrared stealth,the forbidden band of photonic crystal (PC) must be broaden.In this paper,we systematically studied several parameters affect the forbidden bandwidth of PC,such as refractive index ratio,thickness and periodic number of two medium layers.Numeric calculation results show that the forbidden bandwidth increases with the refractive index ratio of two medium layers,and it no longer increases when the refractive index ratio is greater than six; the forbidden bandwidth comes largest when the optical thickness of two medium layers is equal to one quarter of center wavelength respectively; and the periodic number has little influence on the bandwidth.Based on these,we chose PbTe and MgF2 to design a compound PC by four photonic crystals whose center wavelengths are at 10.6μm,4.8μm,2.5μm and 1.06μm respectively,and obtained nearly 100％ reflectance in 1～18μm waveband,which would well meet the demand of the all-infrared waveband stealth.