Spectral reflectance modeling of ZnO layers made with Atomic Layer Deposition for application in optical fiber Fabry-Perot interferometric sensors

Suitability of zinc oxide (ZnO) layers grown using Atomic Layer Deposition for operation in optical-fiber extrinsic Fabry-Perot sensors is investigated using a numerical model. Reflectance spectra obtained using the developed model indicate that the application of these layers in optical-fiber extrinsic Fabry-Perot sensors is difficult as it may require a source whose spectrum width is about 300 nm. A series of ZnO layers grown on end faces of SMF-28 fiber were prepared and their reflectance spectra were recorded by an optical spectrum analyser in order to verify the modelling results. The spectra contain a series of peaks not predicted by the model, which is attributed to two-mode propagation in the SMF-28 fiber connecting the ZnO layer with the rest of the measurement system.