title: Fast detection of humidity with a subwavelength-diameter fiber taper coated with gelatin film.
abstract: A subwavelength-diameter tapered optical fiber coated with gelatin layer for fast relative humidity (RH) sensing is reported. The sensing element is composed of a 680-nm-diameter fiber taper coated with a 80-nm-thickness 8-mm-length gelatin layer, and is operated at a wavelength of 1550 nm. When exposed to moisture, the change in refractive index of the gelatin layer changes the mode field of the guided mode of the coated fiber, and converts a portion of power from guided mode to radiation mode, resulting in RH-dependent loss for optical sensing. The sensor is operated within a wide humidity range (9-94% RH) with high sensitivity and good reversibility. Measured response time is about 70 ms, which is one or two orders of magnitude faster than other types of RH sensors relying on conventional optical fibers or films.
authors: State Key Lab of Modern Optical Instrumentation Zhejiang University, Hangzhou 310027, China.
authors: Lei
authors: L
authors: Zhang
authors: Fuxing
authors: F
authors: Gu
authors: Jingyi
authors: J
authors: Lou
authors: Xuefeng
authors: X
authors: Yin
authors: Limin
authors: L
authors: Tong
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D005780:Gelatin / Q000737:chemistry*; D006813:Humidity; D008567:Membranes, Artificial; D055100:Optical Fibers; D012031:Refractometry / Q000295:instrumentation*; D014159:Transducers; D014867:Water / Q000032:analysis*
chemical_list: D008567:Membranes, Artificial; D014867:Water; D005780:Gelatin