Visible wavelength FBG sensors

• Main Author: Ching, Wei Wen
• Other Authors: Tjin Swee Chuan
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Optics, optoelectronics, photonics
• Online Access: http://hdl.handle.net/10356/60395
• Institution: Nanyang Technological University

The project is to carry out an investigation and development of a modular FBG sensor system that can be mass-produced at an economical cost. By operating FBG sensors in/near the visible light spectrum, it allows the modular FBG sensor to utilize small and cheap super luminescent diode or light-emitting diode and charge-coupled detector as the light source and detector. This would significantly reduce the size and manufacturing cost of the entire modular FBG sensor. Using the phase mask technique, FBGs in the range of 800 – 850nm were fabricated onto single-mode and polarization-maintaining mode fiber. The fabricated FBGs were then studied for their suitability for usage as sensor elements for strain. A simple strain test was setup to determine the linear relationship between the Bragg wavelength and the strain applied to the beam. The FBGs fabricated were first mounted to the surface of an aluminum beam and a vertical displacement strain was then applied onto the beam. The Bragg wavelength and peak intensity were then recorded and studied. It was found that the strain characteristic of the FBGs in the range of 800 – 850nm was similar and comparable to those in 1500nm range. Thus the prospect of operating the FBG sensor in the range of 800 – 850nm seemed very feasible.