title: Optical relative humidity sensor with high sensitivity based on a polyimide-coated symmetrical metal-cladding waveguide.
abstract: An optical structure for relative humidity (RH) sensing based on a polyimide-coated symmetrical metal-cladding waveguide is proposed. The diffusion of water molecules into the polyimide film leads to a combined change of thickness and refractive index. Due to the high sensitivity of ultrahigh-order modes, the interaction between water molecules and polyimide will give rise to a dramatic variation in the reflected light intensity. Our optical RH sensor exhibits a good linearity and a high RH resolution of approximately 0.16% for RH values ranging from 36% to 76%. In addition, it provides a short response time, a favorable stability over a long period, and a small degree of hysteresis.
authors.forename: Wen
authors.initials: W
authors.lastname: Yuan
authors.forename: Xianping
authors.initials: X
authors.lastname: Wang
authors.forename: Yiyou
authors.initials: Y
authors.lastname: Nie
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Minghuang
authors.initials: M
authors.lastname: Sang