| dc.description.abstract | This study aims to develop highly sensitive and multifunctional fiber optic
sensors to overcome the issues associated with existing electronic sensors. The
main research objectives include the fabrication of D-shaped multimode and
single-mode fibers using side-polishing techniques and the deposition of various
materials (such as ??2?5 ???2, ??3) as single-layer thin films on the polished
surfaces using electron gun evaporation. This will lead to the design and
fabrication of high-sensitivity evanescent wave and loss mode resonance (LMR)
fiber optic sensors. The study involves designing and developing three types of
novel fiber optic sensors for glucose solution refractive index, ambient
temperature, and carbon dioxide concentration, as well as optimizing the sensor
fabrication parameters to enhance sensitivity and performance.
Experimental results indicate that the proposed fiber optic sensors exhibit
high sensitivity in detecting the refractive index of glucose solutions, ambient
temperature, and carbon dioxide concentration, demonstrating their potential in
environmental parameter monitoring. For glucose solution refractive index
sensing, D-shaped single-mode and multimode fibers coated with 100 nm ??2?5
thin film, the sensitivity is 6406.44 nm/RIU and 27.723 dB/RIU, respectively. For
temperature sensing in the range of 30°C to 150°C, D-shaped fiber optic sensors
coated with 80 nm ???2 thin film showed the sensitivity is 1.61 nm/°C and
7.68×10-3 dB/°C for single-mode and multimode fibers, respectively. For carbon
dioxide concentration sensing in the range of 500 ppm to 9000 ppm, D-shaped
fiber optic sensors coated with 90 nm ??3 thin film exhibit the the sensitivity is 3.56 counts/ppm and 3.18 counts/ppm for single-mode and multimode fibers,
respectively.
This study′s results indicate that applying different metal oxide films on side
polishing D-shaped fiber optic sensors can effectively enhance the sensitivity to
specific environmental parameters. These evanescent waves and LMR fiber-optic
sensors have advantages in terms of electromagnetic interference resistance, high
sensitivity, environmental durability, safety, long-distance transmission, and high
speed monitoring. | en_US |