Optical waveguide modeling of conducting metal oxide enabled evanescent wave absorption spectroscopy sensors

Recent work has demonstrated significant promise for high temperature optical gas sensing based upon optical property responses in a class of high electronic conductivity metal oxides. In this work, we theoretically simulate the response of aluminum-doped zinc-oxide (an exemplary conducting metal oxide) in optical fiber evanescent wave absorption spectroscopy sensor devices through the application of a general model of the optical constants for this class of materials in conjunction with prior published material-specific constants for the systems under investigation. Theoretical simulations are compared with recently published experimental results for Al-doped ZnO thin films and the various factors responsible for optimizing sensing responses in this class of materials will be discussed.