Comparison of specialty optical fiber and conventional fiber for evanescent sensing applications

• Main Author: Nur Dayana Nurbaythi Mohamed Ali.
• Other Authors: Murukeshan Vadakke Matham
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Mechanical engineering::Mechatronics
• Online Access: http://hdl.handle.net/10356/16203
• Institution: Nanyang Technological University

Evanescent wave sensors are widely used by exploiting the limited penetration depth that evanescent wave possess. This limited depth of penetration calls for the need for the test materials to be in direct contact with the sensing region that is created on the active sensing device – conventional optical fibers. However, due to the development of technology and the increasing demand for better sensitivity in sensors, the use of alternative fibers, i.e. photonic crystal fibers (PCF), emerge as it has displayed huge potential in being highly sensitive and having the ability to sense analytes in solutions. As a proof-of-concept experiment, the sensitivity of the conventional multi-mode fiber and the hollow core PCF were tested by using Rhodamine 6G and Basic Yellow 40 fluorescence solution samples to do single analyte experiments. The ability of these fibers as reliable and accurate evanescent wave sensors were tested and the effects of the concentrations of the analytes on the intensity of wave emitted were investigated. The feasibility of using the hollow core PCF as a multi-analyte evanescent wave sensor was also tested. The initial experiments prove that both the conventional multi-mode fiber and the hollow core PCF were reliable and accurate in reproducing consistent readings, with hollow core PCF giving better results which show that hollow core PCF is much more sensitive than conventional multi-mode fiber for evanescent wave sensing. Results reflected accurately on the direct relationship between the concentration of the analytes and the intensity of the emitted wave. Multi-analyte sensing was shown to be possible, however, due to a shift in measurement observed compared to expected results, more analysis have to be done in this work to bring out the potential of using hollow core PCF for multi-analyte evanescent wave sensing.