FIBEROPTIC EVANESCENT-WAVE PH SENSING WITH DYE-DOPED SOL-GEL FILMS

Sol-gel chemistry is used to incorporate a near-infrared pH sensitive fluorescent dye in a thin-film coated on the core of a multimode fibre . By evanescent wave excitation an absorption or fluorescent sensor ca n be realized for use in high pH regions. Problems associated with thi s configuraiton are discussed. Containment of the evanescent field wit hin the films is investigated with the conclusion that a simple single coat is insufficient, instead careful tailoring of the sol-gel chemis try and multiple coating is necessary.