The development of an evanescent wave optical fiber sensor modified with an organic-inorganic hybrid nanoporous thin film for the detection of organic solvent vapors was demonstrated. The optical fibre with a core diameter of 200 µm was bent into U-shape to enhance the penetation depth of light transferred into the evanescent filed, and modified with a multilayered thin film of poly(allyamine hydrochloride) and silica nanoparticels, (PAH/SiO₂)_n, via layer-by-layer (LbL) film deposition. The mesoporous film structure led to higher molecular diffusion and the highest selectivity to methanol among the six alcohols and water, which were used as target analytes, by the aid of tetrakis(4-sulfophenyl)porphine (TSPP) infused inside the film.