Nitrogen dioxide sensor based on optical fiber coated with a porous silica matrix incorporating lutetium bisphthalocyanine

In this work, we present the results of a sensor exploiting a coating consisting of lutetium bisphthalocyanine (LuPc₂) dispersed in a porous silica matrix deposited by a sol-gel process. LuPc₂ shows a gasochromic effect in the telecommunication wavelengths range. The absorption spectrum in this range strongly decreases in contact with NO₂. The sensor consists then in a coating deposited on a single-mode silica fiber tip in order to form a Fabry-Pérot cavity. An amplitude change in the reflected spectrum is observed after contact with 1 ppm NO₂ thus showing its sensitivity to that gas.