Optic fiber humidity sensor based on MZI-SMF.

• Main Author: Chia, K. H.
• Other Authors: Chan Chi Chiu
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Engineering::Bioengineering
• Online Access: http://hdl.handle.net/10356/50509
• Institution: Nanyang Technological University

In this project, the feasibility of a new type of fiber-optic humidity sensor based on a Mach-Zehnder Interferometer (MZI) in a normal single-mode fiber (SMF) with waist-enlarged fusion bitapers is explored. A special coating of chitosan is adhered to the cladding mode of the optical fiber, and this chitosan expands in response to the presence of water vapour, causing interference of light within the fiber. The resulting spectra analysis displays significant phase changes when relative humidity is increased from 10% to 90% at increments of 5%. The resolution of the linear analysis of wavelength shift versus relative humidity results in a value of 0.11nm/humidity unit and the maximum wavelength shift obtained for the sensor is 9.8nm.