Effect of doping swelling polymer cladding with phthalocyanine dye inplastic optical fiber humidity sensors

摘要

We have developed and tested plastic optical fiber (POF)-type humidity sensors, which consist of a dye-dopedswelling polymer cladding. POF-type humidity sensors consist of a hydroxyethyl cellulose or polyvinylpyrrolidone(PVP) cladding layer that surrounds a poly(methyl methacrylate) core. The operation of these sensors is based on thechange in refractive index caused by swelling of the cladding layer. To improve the sensitivity of the humidity sensor,we have investigated the effect of doping the cladding polymer with phthalocyanine dye. The results indicate that thePOF-type humidity sensor using PVP is three times more sensitive for relative humidities above 80% when the dye-doped swelling-polymer cladding is used.