  In this study, we describe the formation of ZnO nanolayers inside the air
capillaries of a silica photonic crystal fibre (PCF), targeting random laser
and organic vapor sensing applications. ZnO nanolayers were developed by
infiltrating the capillaries of the silica PCF with Zn-acetate/methanol
solutions of various concentrations, followed by annealing treatments. The
growth and morphology of the synthesized ZnO nanolayers were characterized by
means of scanning electron microscopy (SEM) and found to be affected by the
concentration of the Zn-acetate/methanol infiltration solution. For low
concentrations, inspection with SEM revealed the formation of 25 and
100-nm-thick ZnO nanolayers across the entire length of the infiltrated
capillaries, whereas increasing the Zn-acetate concentration resulted to the
formation of randomly placed isolated ZnO nanorods. Room temperature
photoluminescence spectra of the ZnO nanolayers inside the PCF were measured
and compared with the corresponding spectra reported for ZnO structures formed
on typical surfaces.
