An optical relative humidity sensor based on the enhanced Goos-Hanchen shift

A high-sensitivity optical relative humidity (RH) sensor based on the enhanced Goos-Hanchen (GH) shift in a polyimide-coated symmetrical metal cladding waveguide is proposed. The interaction between the diffused water molecules and the polyimide film can lead to a combined change in the thickness and the refractive index, which will give rise to a dramatic change of GH shift. Our optical RH sensor can provide a good linearity and a short response time.