Hydrophobic alumina thin films formed by the electrostatic self-assembly monolayer process for the fabrication of optical fiber gas sensors

Aluminum oxide thin films were formed by the electrostatic self-assembled monolayer (ESAM) method on optical fibers for the fabrication of gas sensors. Negligible sensitivity with humidity was achieved after thermal curing a variation of 1.5 dB at 1550 nm was achieved with the presence of ethanol. The coatings are also sensitive to other organic compound, this apparent lack of selectivity can be overcome with wavelength ratiometric techniques because the spectral response to these gases is different for each gas and this open the possibility of the simultaneous detection of several compounds. This is the first time that the ESAM method have been applied for the deposition of alumina films on optical fibers.