Experimental investigation of a surface plasmon-basedintegrated-optic humidity sensor

Abstract

A humidity sensor has been fabricated by coating a surface plasmon waveguide with a thin layer of Nafion fluoropolymer. The refractive index of Nafion varies as a function of humidity, causing a shift in the plasmon resonance wavelength. The present device is able to measure relative humidity over a range of at least 20% to 50%, while exhibiting good linearity. Furthermore, humidity-induced index changes to Nafion occur rapidly and appear to be fully reversible.