Modeling of a Fabry-Perot filter based on TiO2 and air gap by using Eigenvectors and Eigenvalues approach

Abstract

We used Eigenvectors and Eigenvalues method to obtain transmittance coefficients for each of an interference filter. The filter is based on titanium dioxide layer (n=2.26) and air (n=1.0). The transmission spectra of the FP filter in mid- IR region shows a characteristic peak with a maximum of 86 % at 4.70 μm which is the fundamental absorption wavelength of CO which makes it possible to work as a gas sensor. The layers are horizontally stacked on one side which makes it possible to use air as a low index material. This gives an opportunity to deposit high index material in single deposition step which transforms the layer thickness into line thickness. As a result complex filter designs can be fabricated with simple and low production cost.