Open AccessFast detection of humidity with a subwavelength-diameter fiber taper coated with gelatin film
Author(s) -
Lei Zhang,
Fuxing Gu,
Jingyi Lou,
Xingtian Yin,
Limin Tong
Publication year - 2008
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.16.013349
Subject(s) - materials science , optics , gelatin , refractive index , optical fiber , relative humidity , fiber , wavelength , layer (electronics) , fiber optic sensor , optical power , optoelectronics , composite material , laser , biochemistry , chemistry , physics , thermodynamics
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.