NO2 optical fiber sensor based on TFBG coated with LuPc2

We present an optical fiber sensor based on a tilted fiber Bragg grating (TFBG) coated with lutetium bisphthalocyanines (LuPc
₂
) for nitrogen dioxide (NO
₂
) measurement. The measurand is encoded in the peak-to-peak amplitude of the cladding resonances since they are modified with the gas presence. A specifically developed peak/valley detection algorithm was used for the gas monitoring. Ultra-violet (UV) illumination of the coating is needed in order to recover the sensitive material to its original state after NO
₂
exposure. The sensor responds properly to several cycles in presence and in absence of NO
₂
.