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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 16, Iss. 17 — Aug. 18, 2008
  • pp: 13349–13353

Fast detection of humidity with a subwavelength-diameter fiber taper coated with gelatin film

Lei Zhang, Fuxing Gu, Jingyi Lou, Xuefeng Yin, and Limin Tong  »View Author Affiliations

Optics Express, Vol. 16, Issue 17, pp. 13349-13353 (2008)

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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.

© 2008 Optical Society of America

OCIS Codes
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(310.6628) Thin films : Subwavelength structures, nanostructures
(240.3990) Optics at surfaces : Micro-optical devices

ToC Category:
Fiber Optics and Optical Communications

Original Manuscript: July 8, 2008
Revised Manuscript: August 6, 2008
Manuscript Accepted: August 8, 2008
Published: August 14, 2008

Lei Zhang, Fuxing Gu, Jingyi Lou, Xuefeng Yin, and Limin Tong, "Fast detection of humidity with a subwavelength-diameter fiber taper coated with gelatin film," Opt. Express 16, 13349-13353 (2008)

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