Product Code: ICA11_M805

Sensitivity Analysis of Fiber Bragg Grating Sensors Coated by Metallic Films Produced by the Laser-Assisted Maskless Microdeposition Process
Authors:
Xixi Zhang, University of Waterloo; Waterloo ON Canada
Hamidreza Alemohammad, University of Waterloo; Waterloo ON Canada
Ehsan Toyserkani, University of Waterloo; Waterloo ON Canada
Presented at ICALEO 2011

The sensitivity required for optical fiber sensors such as fiber Bragg gratings (FBG) is highly dependent on applications, environment of use and the magnitude of measured physical parameters. Such sensitivity dependencies are more complicated if FBGs are embedded in metallic structures using laser-assisted additive manufacturing. One of the methodologies for the improvement of the sensitivity of FBGs is to coat them with conductive thin films. The coating not only protects the optical fiber sensor but also improves its sensitivity. The coating process proposed in this paper entails two steps: 1) Laser Assisted Maskless Microdeposition (LAMM) to fabricate a conductive thin silver film on the FBG sensor, 2) electroless plating to plate nickel on the silver-coated sensor. In LAMM, silver nano-particles are injected on a moving substrate, and then sintered by a laser beam. By using LAMM, the silver films can selectively be deposited on FBGs without compromising their integrity. The film of silver will facilitate the electroless plating while improving the sensitivity of the sensors. As the nickel electroless plating is an auto-catalytic process performed at a 90°C chemical solution bath, nickel will be plated on silver effectively with a controlled thickness. The effect of the thickness of the nickel layer on the sensitivity will be discussed in the paper. In addition, the role of laser parameters on the coating characteristics such as bonding will experimentally be investigated.