Numerical Simulation of the Optical Coatings based on Ag Infrared Reflector

Ultra-thin metal layer (thickness below 15 nm) is of great interest as optical coatings in heat reflectors systems. However, producing these thin layers has been a continuing challenge because their thicknesses of individual layers depart from the conventional values. In this work, Infrared Reflective Optical Coatings are designed using thin layers to the visible transmittance at wavelengths 400~800 nm while reflecting infrared wavelengths 800-3000 nm. Three different design approaches have been used, namely single layers of metal (Ag), bi-layers design metal/ dielectric structure, and multilayer systems were designed on glass substrates for reflectors applications. The dielectrics materials (SiO2, SiN, Nb2O5, CdTe and AlAs) are chosen in this study. A detailed mathematical analysis based on characteristic matrix theory is presented to predict heat Multilayers reflectors. The optical performance of three alternating layers Nb2O5(25nm)/Ag(15nm)/Nb2O5(25nm) on substrate in range of (400-3000 nm) show the maximum visible transmittance about 89% and maximum IR reflectance 83. % at 1900 nm with stack SiO2(25nm)/Ag(15nm)/SiO2(25nm). Also the designs of stacks SiO2 (25nm) /Ag (15nm)/ SiO2(25nm)/ Ag(15nm)/ SiO2(25nm) and SiN (25nm) / Ag (15nm) /SiN (25nm)/Ag(15nm) / SiN(25nm) show the maximum reflection of IR wavelengths compared to the three alternating layers structure.