Optical waveguide sensor using evanescent wave excitation of fluorescent dye in sol-gel glass

The sol-gel process for low temperature fabrication of porous glass has been used to entrap chemically-sensitive dyes for optical sensor applications. Evanescent wave excitation was used to examine the behaviour of an unclad fibre which was dipcoated with a thin layer of porous cladding within which a pH-sensitive dye was entrapped. The performance of the pH sensor is reported and the potential of the technique for distributed and integrated optic sensing is discussed.