Optical response of multilayer thermochromic VO2-based structures

We considered the emissivity properties of VO2 thin films as a function of temperature through several simulations, considering different substrates and multilayer structures. Formulating the concept of emissivity tunability is introduced and we found that a large difference in emissivity, below and above the transition temperature, can be obtained which may be used for the design of medium-wave infrared (3 to 5 mu m) filters. Specifically, we optimized a multilayer structure, to function as a low-emissivity filter, at high temperature for the reduction of infrared signature. The values of emissivity changes, found for a VO2/metal multilayer, are larger than the value of a single layer of VO2. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.JNP.6.061601]