Vanadium oxide thin films for optical readout-based thermal imager

In this study, optical characterization of vanadium oxide (VOx) thin film is performed using a variable angle spectroscopic ellipsometer (VASE). The characterization is performed at four different room temperatures, 25.5–28.5 °C, in steps of 1 °C. The best fitting results of the ellipsometric parameters φ and Δ are obtained by using a GenOsc layer with the Lorentz oscillator. Four different thermo-optic coefficients (TOCs) are obtained from the modelled data. The TOC value with the least extinction coefficient is chosen, which occurs at 26.5 °C. The effect of the TOC value on shifting the Fabry-Perot cavity filter (FPCF) tuning frequency is examined on all designs (2, 4, and 6 stacks) to determine the sensitivity of the FPCF sensor in scene temperature variations. We verify the performance of the sensor as a long-wave infrared radiation absorber and as a visible light band-pass filter. This sensor is designed to have a low thermal conductivity and a low mechanical stress.